I have a test on Monday for Microeconomics, this is the last subject I have left to understand, I have asked this question previously in Course Hero, although I didn't feel satisfied with the answer. The Question is: Baskets A,B,C,D and E are at the budget constraint of this person

Suppose that the following graph shows the budget constraint of a person that always pays a dollar for one unit of the Y good, he pays one dollar for the first four units of the X good, and four for each extra unit of this good.