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
User Interface API should be used to implement this integration. User Interface API is a RESTful API that allows you to create native mobile apps and custom web apps with the look and feel of Salesforce's Lightning Experience. User Interface API provides access to metadata, data, and UI components, such as layouts, actions, picklists, and record types. User Interface API also handles security, performance, and compatibility across different devices and browsers. References: Certification - Integration Architect - Trailhead, [User Interface API Developer Guide]

Explanation
The mobile device should make a REST Apex inbound call to meet the requirement. A REST Apex inbound call allows the mobile device to invoke custom Apex logic on Salesforce using a RESTful interface. The Apex logic can then access the geolocation field using the user's OAuth token and update it with the GPS coordinates from the mobile device. The geolocation field is secured with Field Level Security, so the user can view the value without changing it. A SOAP API inbound call or a REST API inbound call would not be able to access the custom geolocation field, as they are not supported by the standard Salesforce objects and fields.
Reference: Salesforce Integration Architecture Designer Resource Guide, page 20

https://developer.salesforce.com/docs/atlas.en-us.platform_events.meta/platform_events/platform_events_define_ui.htm