A company uses Salesforce to store accounts and contacts.

Option A is correct because Customer 360 Data Manager can be used to ensure that there is only a single contact for a particular person across all the subsidiaries of a company. Customer 360 Data Manager is a tool that enables data integration and identity resolution across multiple Salesforce clouds and external systems. It can match and merge duplicate contacts based on various criteria and create a single source of truth for customer data.

Option C is correct because Duplicate Matching Rules can be used to ensure that there is only a single contact for a particular person across all the subsidiaries of a company. Duplicate Matching Rules are rules that define how Salesforce identifies duplicate records based on standard or custom fields. They can prevent users from creating or updating duplicate contacts based on various criteria and actions.

Option B is incorrect because Third-party application or AppExchange tool is not an option that the Solution Architect can use to ensure that there is only a single contact for a particular person across all the subsidiaries of a company. Third-party application or AppExchange tool is not a specific or native solution for this problem, but rather a general or external solution that may or may not work depending on the features and compatibility of the application or tool.

Option D is incorrect because Lightning Data Services is not an option that the Solution Architect can use to ensure that there is only a single contact for a particular person across all the subsidiaries of a company. Lightning Data Services is a tool that enables developers to access, cache, and modify data in Lightning web components without using Apex code. It does not have any functionality to prevent or resolve duplicate contacts.

References:

[Get Started with B2C Solution Architect Cert Prep - Trailhead]

[Certification - B2C Solution Architect - Trailhead]

B2C Solution Architect Certification Guide | Salesforce Ben