Does ( rainfall - the amount of rain that falls in a country ) determine how the country develops ?

Yes, rainfall does affect how a country will develop. The most important thing to any developing country is agriculture. The type of agriculture practiced in a certain region or country in the world depends on the type of climate, which includes rainfall. For example in dry climates, pastoral nomadism is a common type of agriculture, and in humid climates plantation agriculture is common. Additionally, some agricultural practices are more commercial, like plantation agriculture, while others are subsistence, such as pastoral nomadism. So the type of agriculture also affects how the economy will grow.

the correct answer is b.