3) "The catch-up effect" says that countries with low income can grow faster than countries with higher income.

a. What is the mechanism that makes the cath-up effect a plausible statement (i.e., what is the reasoning for the catch-up effect)? Briefly explain. (10 p.)

b. Despite the catch-up effect, why don't we observe poor countries catching the rich ones in income per capita in real life? (15 p.)