A data breach is broadly defined as any incident that leads to the unauthorized access, disclosure, alteration, or destruction of personal data. While options A and B might seem plausible at first glance, they focus on a narrow interpretation of a breach.
The key here is the loss of confidentiality and/or integrity. Even though no one has actively stolen the data, the bank can no longer guarantee the confidentiality of the information, nor can it ensure the integrity of the data since it cannot be accessed or modified securely. This constitutes a loss of control over the data and thus qualifies as a data breach.
Reference:
IAPP CIPP/E textbook, Chapter 5: Data Breach Notification (specifically, the definition of a personal data breach) GDPR Article 4(12) - Definition of a personal data breach

Explanation/Reference: https://ico.org.uk/for-organisations/guide-to-data-protection/guide-to-the-general-data-protection- regulation-gdpr/accountability-and-governance/data-protection-officers/

The NIS2 Directive is the EU's legislation on cybersecurity that updates and replaces the previous NIS Directive. It aims to create a high common level of cybersecurity across the EU by setting up legal measures for the security of network and information systems used by essential and important entities in various sectors and by enhancing cooperation among the member states. The NIS2 Directive does not establish a common controls framework that every organization must adopt, but rather allows each member state to define the appropriate security measures and incident reporting requirements for the entities under its jurisdiction, taking into account the specificities of each sector and subsector. However, the NIS2 Directive does provide some general principles and objectives for the security measures, such as proportionality, risk-based approach, state of the art, and regular review and update. The NIS2 Directive also introduces minimum harmonised rules for the supervision and enforcement of the security measures and incident reporting obligations, including the possibility of imposing administrative fines.
Reference:
NIS2 Directive, Articles 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, and 14.
The NIS2 Directive: A high common level of cybersecurity in the EU, pages 1, 2, 3, 4, 5, 6, 7, and 8.

The aim of the European Data Protection Directive 95/46/EC was to establish a common legal framework for the protection of personal data within the European Union, and to ensure the free movement of such data within the internal market. The Directive was based on the recognition that the processing of personal data affects the fundamental rights and freedoms of individuals, especially their right to privacy, and that these rights need to be respected and safeguarded. At the same time, the Directive acknowledged that the free flow of personal data is essential for the economic and social development of the EU, and that the harmonization of data protection laws would facilitate the exchange of information and the provision of services across the member states. Therefore, the Directive aimed to strike a balance between the protection of individuals' rights and the promotion of the internal market, by laying down the key principles, obligations and rights for the processing of personal data, and by providing mechanisms for cooperation and coordination among the national data protection authorities. References: Directive 95/46/EC of the European Parliament and of the Council of 24 October 1995 on the protection of individuals with regard to the processing of personal data and on the free movement of such data, Data Protection Directive - Wikipedia

The Individual Participation Principle is one of the Fair Information Practice Principles (FIPPs) that are not part of any legal framework, but are widely adopted by many data privacy regulations in force today1. The FIPPs are a set of guidelines for fair information practices that aim to protect the privacy and security of personal information. The Individual Participation Principle holds that individuals have a number of rights, including the right to have their personal data corrected or erased, the right to access and obtain confirmation of their personal data, the right to be informed about how their personal data is used and who it is shared with, and the right to object or withdraw consent for certain purposes2.
The General Data Protection Regulation (GDPR) is a legal framework that implements the European Union's (EU) Data Protection Directive and provides comprehensive protection for all individuals within the EU regarding their personal data. The GDPR grants individuals a number of rights, such as the right to access, rectify, erase, restrict, port, object, or not be subject to automated decision-making based on their personal data. These rights are similar to those under the FIPPs and can be found in Articles 12 to 22 of the GDPR.
Therefore, the parts of the GDPR that provide the closest equivalent to the Individual Participation Principle are Articles 12 to 22.
Reference:
OECD Privacy Principles
What are the 7 main principles of GDPR?
Fair Information Practice Principles (FIPPs)
Individual Participation - International Association of Privacy Professionals What is the right to be forgotten? | Right to erasure | Cloudflare General Data Protection Regulation - Wikipedia