CPM Homework Help : APCALC Problem 7-93

Brooke and Anne came across this integral: $y =\int dx$ . Brooke says it cannot be evaluated because there is nothing to integrate. Anne says the answer is $y = x + C$ . Who is correct and why?

Hint:

An integral is the sum of infinitely many rectangles with infinitely small widths.
The base of each rectangle is represented as $dx$ . The height is the integrand.
Though you cannot see the integrand, it is there.