A large retail B2C customer wants to build a 360-degree view of its customers for its call center agents. The customer i

[answerhappygod]

A large retail B2C customer wants to build a 360-degree view of its customers for its call center agents. The customer information is currently maintained in the following systems:
1. Salesforce CRM
2. Custom billing solution
3. Customer master data management (MDM)
4. Contract management system
5. Marketing solution
What should a data architect recommend that would help uniquely identify the customer across multiple systems?

A. Store the Salesforce ID in all the solutions to identify the customer.
B. Create a custom field as external ID to maintain the customer ID from the MDM solution.
C. Create a custom object that will serve as a cross-reference for the customer ID.
D. Create a customer database, and use this ID in all systems.