Jake was \(4\frac12\) feet tall on his \(12th\) birthday when he began to have a growth spurt. Between his \(12th\) and \(15th\) birthdays, he grew at a constant rate. If Jake was \(20\%\) taller on his \(15th\) birthday than on his \(13th\) birthday, how many inches per year did Jake grow during his growth spurt? (\(12\) inches =\(1\) foot)

A. 4
B. 5
C. 6
D. 7
E. 8

Answer: C

Source: Manhattan GMAT