https://trailhead.salesforce.com/en/content/learn/modules/change-data-capture/understand-change-data-capture

Explanation
Platform Events are a type of event-driven architecture that allows you to publish and subscribe to events in Salesforce and external systems. To subscribe to an event, the integration user in Salesforce needs read access to the event entity, which defines the schema and properties of the event message. To publish an event, the integration user in Salesforce needs create permission on the event entity, which is a special type of sObject that can be inserted into the platform event queue. Error handling must be performed by the remote service because the event is effectively handed off to the remote system for further processing. Salesforce does not guarantee the delivery or acknowledgment of the event by the external system. The external system should implement its own logic to handle errors, such as retrying failed events, logging errors, or sending notifications. References: Certification - Integration Architect - Trailhead, [Platform Events Developer Guide]

Explanation
Option D is correct because Tooling API is the Salesforce API that can be used to retrieve code coverage and test results for Apex classes and triggers. Tooling API provides REST and SOAP interfaces to access metadata about code, execute tests, and get test results12 Option A is incorrect because SOAP API is a Salesforce API that can be used to create, retrieve, update, or delete records, but not to get code coverage and test results. SOAP API uses a WSDL file to define the parameters for accessing data through the API3 Option B is incorrect because Analytics REST API is a Salesforce API that can be used to access data from reports and dashboards, but not from code coverage and test results. Analytics REST API provides a programmatic way to interact with analytics features such as lenses, datasets, and dashboards4 Option C is incorrect because Metadata API is a Salesforce API that can be used to retrieve, deploy, create, update, or delete customization information, such as custom object definitions and page layouts, but not code coverage and test results. Metadata API is mainly used for development tools or backup tools5 References: 1: Introducing Tooling API 2: Tooling API Examples 3: SOAP API Developer Guide 4: Analytics REST API Developer Guide 5: Metadata API Developer Guide

Explanation
The three systems from the current system landscape that can be retired with the implementation of Salesforce are Case Management System, Sales Activity System, and Email Marketing System. These systems can be replaced by Salesforce Service Cloud, Sales Cloud, and Marketing Cloud respectively, which provide similar or better capabilities for managing cases, sales activities, and email campaigns. Option A is not correct because Order Management System cannot be retired with the implementation of Salesforce. The company wants to reuse their existing enterprise capabilities for order management processes, which are likely to be complex and customized. Salesforce does not provide a native order management solution for B2C commerce scenarios. Option E is not correct because Quoting System cannot be retired with the implementation of Salesforce. The company wants to reuse their existing enterprise capabilities for quoting processes, which are likely to be complex and customized. Salesforce does not provide a native quoting solution for B2C commerce scenarios.

https://help.salesforce.com/articleView?id=collab_files_overview.htm&type=5