What need to be done to make the metric available on the Account forecast component?

An admin wants to create new custom metric on the Account product period forecast component.

What need to be done to make the metric available on the Account forecast component?
A . Create a custom field on Account Forecast, create a custom of field on account product, map both of new fields in the account forecast setting page.
B . Create a custom of field on account product period forecast, , create a custom of field on account product forecast, map both of new fields in the account forecast setting page.
C . Create a custom of field on Sales agreement product, Create a custom of field on Sales agreement product period, map both of new fields in the Sales agreement setting page
D . Create a custom of field on account forecast adjustment, Create a custom of field on account forecast adjustment period, map both of new fields in the account forecast setting page.

Answer: B