No. C is wrong.
Active voice is used when the subject is doing the action.
Customers are served . . .
Customers is the subject, but they are not doing the action. They're just sitting there waiting for the wait staff.
The subjects of each of these sentences is the first word. In which one are they doing the action?
This site should also help you.
https://webapps.towson.edu/ows/activepass.htm
Which sentence uses the active voice?
A. Breakfast is always served at 8 a.m. sharp.
B. Juice is included in all breakfast meals.
C. Customers are served as quickly as possible.
D. You can have anything that you find appealing.
I don't really understand active and passive voices but I think the answer is C) Customers are served as quickly as possible.
3 answers
After looking over Ms.Sue's link I feel as if the answer is D) You can have anything that you find appealing.
Because the customers are choosing their food/performing the action?
Because the customers are choosing their food/performing the action?
Yes, D is in the active voice.