You can interpret the function notation at different values. For example, a worker's pay each month, p(h), depends on the hours of training, h. The table shows the meaning of the function notation for different inputs and outputs.

Function notation
Meaning
p(30) = 2500
A worker with 30 hours of training is paid $2500 a month
p(60) = 3000
A worker with 60 hours of training is paid $3000 a month.
The area of a square (in square feet) depends on the length of its sides (in feet). This is written in function notation as a(s).

What is the best interpretation of a(3) = 9?

A. 3 sides of the square have a total length of 9 feet.
B. 3 of these squares have a total area of 9 square feet.
C. A square with an area of 3 square feet has side lengths of 9 feet.
D. A square with side lengths of 3 feet has an area of 9 square feet.