Why do very small differences in annual growth rates amount to big dif

Why do very small differences in annual growth rates amount to big differences in the degree of long-term economic growth?

A) because the slower-growing countries save too much
B) because the annual growth rate is compounded over time
C) because the faster-growing countries gain a political advantage over poorer countries, and use that advantage for their economic gain
D) because the slower-growing countries don’t export enough

ANSWER

B