To really understand a world without humans, I realized I would have to learn what the world was like before humans evolved. So I went to Africa, the place where humans arose and the only continent where there are still huge animals roaming around. We used to have huge animals on all the other continents and on many of the islands. We had enormous creatures in North and South America – giant sloths that were even bigger than the mammoths, beavers the size of bears, etc. _____________________
The question is confusing as all options are close. However, this question has been directly taken from a passage which ends with the option (c). There are some clues to arrive at the right answer. The last sentence of the passage indicates that humans may have something to do with the extinctions of the huge animals. [b], which mentions climate change but not humans, is therefore wrong. [a] contradicts the last sentence, as clearly, there are some clues that tie the animals’ extinctions to the arrival of humans. [e] is also contradictory, as the passage seems to hold humans responsible for the extinctions, not climate change. Indeed, there is no mention of climate change in the passage at all, so [d] goes beyond its purview. This leaves us with [c] as the best answer. Hence, [c].