How should the report be identified to include the number of individual accounts represented by representative?

In Lightning, an opportunity pipeline report listing opportunities by sales representative shows multiple opportunities written for the same account. The sales Manager would like to know how many individual account each representative has written business for.

How should the report be identified to include the number of individual accounts represented by representative?
A . Create a custom summary formula and group by account.
B . Select Show Unique Count on the Account Name Column in the report builder.
C . Add a bucket field for Account Name and group by the bucket field.
D . Group by Account and summarize a custom checkbox defaulted to checked.

Answer: A