How can this visual indicator be displayed?

A custom field contains a feedback score which is on a scale of one to five. End users would like a visual indicator of one to five stars based on the number found in the feedback score custom field.

How can this visual indicator be displayed?
A . Use a custom number field.
B . Use a custom image field.
C . Use a custom formula field.
D . Use a custom text field.

Answer: C