Answer:
B. 733 customers
Explanation:
15+30+45=90
since 30 people select a black frame, 1/3 of the customers picked black frames. If this data is consistent through the month (which we have to assume it is) then that means 1/3 of customers select a black frame on average. 1/3 of 2,200 is about 733, so we can assume, using the data given, that about 733 customers selected black frames! :)