The area of a square depends on the length of its sides. This can be written in function notation as a(s). What is the best interpretation of a(4) = 16?

A. The area of a square is always one-fourth of the side length.

B. The area of a square is always four times the side length.

C. A square with sides 4 units long has an area of 16 square units.

D. A square with sides 16 units long has an area of 4 square units.​