Given that income is $300, the price of good Y is $15, and the price of good X is $20. What is the vertical intercept of the budget line?

Given that income is $300, the price of good Y is $15, and the price of good X is $20. What is the vertical intercept of the budget line?

A.   4500

B.   300

C.   20

D.   15

I might be able to guess at this, or at least narrow down the possible answers, but I want to understand this information, so I can perform it on the test.  Please explain your answer.