So you have the equation y = 3x + 22.
x = months starting after 2014
y = total number of comic books
So think about it, when x = 0, y= 22, which means that he started with 22 comic books
When x=1 (meaning after 1 month), y = 25, so after 1 month the amount of comic books increased by 25-22 = 3.
So you can see the answer is C.