Which hypothesis mentioned in the book proposes that equatorial regions are poor because tropical diseases have consequences for health and production and that tropical soils do not allow for productive agriculture?

The answer is the Geography Hypothesis.

Explanation:

The geography hypothesis holds that the differences in prosperity that are found around the world are due in large part to forces of nature, like the differences in geography, climate, and ecology that are evident in different regions of the world. The geography hypothesis emphasizes how the natural environment can explain why some nations are more prosperous than others. In contrast, the institutions hypothesis emphasizes the influences that are made and caused by humans. Human poverty is largely man-made in the institutions view.  

since there isn't any suggested answers i will give you the reason and hopefully you can figure it

south africa, or rather all of africa, has not been in the location in which it is nowadays throughout the geological past. after the super-continent pangaea started to break apart, gondwanaland, in which was africa, moved further south, and parts of it came to be very close to the south pole. because the climate in this part of the world is very cold due to the very dispersed sun rays in there, what is now south africa, started to freeze, and the conditions were right for the formation of glaciers. the glaciers existed up until the period when gondwanaland started to break apart and what is now africa started to move towards north, sp it warmed up and the glaciers melted.