A backdoor is a method of bypassing normal authentication procedures.
Many computer manufacturers used to preinstall backdoors on their systems to provide technical
support for customers. Hackers typically use backdoors to secure remote access to a computer,
while attempting to remain hidden from casual
inspection. To install backdoors, hackers prefer to use either Trojan horse or computer worm.

Resilience is the ability of an organization to continue to operate effectively during or after a disruptive event.
A business impact analysis (BIA) is a key process to identify the critical systems and processes that support the organization's objectives and determine the impact of their disruption. Without a BIA, the organization may not be able to prioritize the recovery of the most important systems and processes, which poses the greatest risk to its resilience. The other options are not as significant as a BIA, as they relate to data quality, system monitoring, and user acceptance testing, which are important but not essential for resilience.
References: CISA Review Manual (Digital Version), Domain 4: Information Systems Operations and Business Resilience, Section 4.2 Business Continuity Planning1

The only thing that can be provided by asymmetric encryption is nonrepudiation. Nonrepudiation is the ability to prove that a message or transaction was originated or authorized by a specific party. Asymmetric encryption uses a pair of keys: a public key and a private key. The public key can be shared with anyone, while the private key is kept secret by the owner. If a message is encrypted with the sender's private key, only the sender's public key can decrypt it. This proves that the message was sent by the sender and not by anyone else.
This is called digital signature and it provides nonrepudiation. Asymmetric encryption can also provide information privacy by encrypting a message with the receiver's public key, so that only the receiver's private key can decrypt it. However, information privacy can also be provided by symmetric encryption, which uses a single key to encrypt and decrypt messages. References:
* CISA Review Manual (Digital Version), Chapter 5, Section 5.21
* CISA Online Review Course, Domain 3, Module 2, Lesson 12