D. Create a cross-object formula field on the Account.

This approach allows you to calculate and display the total values of open opportunities directly on the account record, taking into account the different currencies1.
Note: While Advanced Currency Management supports dated exchange rates for opportunities, it does not support roll-up summary fields that calculate currency on the opportunity object rolling up to the account object1. Therefore, option C is not viable in this context.
https://help.salesforce.com/s/articleView?id=sf.administration_about_advanced_currency_management.htm&type=5

answer is B