How should the consultantimplement a solution to meet the requirement?

Cloud Kicks is expanding its operations to Europe. The company wants to enable able Advanced Currency Management to support both EUR and USD currencies, and show the total values of open opportunities on account records.

How should the consultantimplement a solution to meet the requirement?
A . Use a custom summary formula field on the Opportunity.
B. Install a third-party app from the AppExchange.
C. Use a Roll-up Summary field from the Opportunity to the Account.
D. Create a cross-object formulafield on the Account.

Answer: A