I actually think the correct answer is C.
Only the definite integral is approximated using area.
The antiderivative, or the indefinite integral, represents a function whose derivative gives you 0. Any constant does this.
Think about it: the derivative of 5 is 0. The derivative of 17 is 0. The derivative of -2/3 is 0.
So when you're asked, what is the antiderivative of 0? You have to say, it's some constant.
Now the definite integral, on any interval [a, b], has to be 0, for the reasons mentioned by dylalien.