You need to create an indexed view that contains an aggregation.
Which function is required in the view definition?

A.
MAX

B.
COUNT_BIG

C.
COUNT

D.
SUM

Explanation:
COUNT_BIG is a scalar aggregate function.
The capability of the query optimizer to take advantage of indexed views when it processes queries has
improved over earlier version, such as support for aggregate functions.
For example, the following query that contains a scalar aggregate function in its SELECT list:
SELECT COUNT_BIG (*) FROM dbo.TableT
Can be matched with an index created on this view:
CREATE VIEW V2 WITH SCHEMABINDING AS
SELECT COUNT_BIG (*) AS Cnt
FROM dbo.TableT
Note: COUNT_BIG returns the number of items in a group. COUNT_BIG works like the COUNT function. The
only difference between the two functions is their return values. COUNT_BIG always returns a bigint data type
value. COUNT always returns an int data type value.

https://technet.microsoft.com/en-us/library/ms187864(v=sql.105).aspx