.63, 69%, 0.72, 3/4, there you gooooo
So, we have 4 cups of flour and 6 cups of sugar and we need to know how many cups of sugar per cup of flour does the recipe require. Because it is requested to know how many cups of sugar per cup of flour does the recipe require, we need to divide the amount of flour and sugar by the amount of flour, and we will know what we need to know.
4 cups of flour / 4 = 1 cup flour
6 cups of sugar / 4 = 6/4 = 3/2 = 1 1/2 cups of sugar per cup of flour is the solution
Weird that the only choices are given as integrals with respect to

. (Integration along the

axis would be way easier, but whatever)
The fourth option should do it.
You are correct. The answer is choice C.
The other choices A, B, D have each side add up to 180 degrees either because the angles are a linear pair (adjacent and supplementary) or because the angles are same side interior angles. Same side interior angles are supplementary if a transversal line cuts through a pair of parallel lines as so happens in this diagram.