Let f(x) = √(36 - x2). Set up the integral that will give the arc length of the graph of f(x) over the interval [0,6].

What is the integral that will give the arc length of the graph of f(x) over the interval [0,6]?
A) ∫[0,6] √(36 - x2) dx
B) ∫[0,6] √(x2 - 36) dx
C) ∫[0,6] √(x2 + 36) dx
D) ∫[0,6] √(x2 - 36) dx