Which field is used to uniquely identify an individual across multiple channels in Marketing Cloud Engagement?

Which field is used to uniquely identify an individual across multiple channels in Marketing Cloud Engagement?
A . Email Address
B . Contact Key
C . Mobile Number

Answer: B

Explanation:

The Contact Key is used to uniquely identify an individual across multiple channels in Marketing Cloud Engagement. It serves as a unique identifier for each contact in the system, allowing for the integration and coordination of marketing activities across different channels such as email, mobile, social, and others. The Contact Key remains consistent for a given individual across different interactions and campaigns, providing a unified view of the customer.