Question

How could the change in surface temperatures shown in the graph most likely impact tropical areas?

There are fewer hot and humid days, and species will migrate north.
There is less available sunlight, and kelp forests will become less dense.
There is less average global ice, and coral bleaching will occur.
There is greater primary productivity, and animal abundance will increase.

Answer 1

There is less average global ice, and coral bleaching will occur/

There is a pattern of stronger storms and coral bleaching will occur.

The tropics refers to that part of the universe that is marked off by high temperatures. The humidity in these areas in always very high thus the regions are always hot. These regions are also known to support the growth of luxuriant vegetation.

The key is "Tropical area". There is practically no kelp in the tropics (eliminate 2). Temperature increases - there are MORE hot days, NOT FEWER (eliminate option 1), and animal abundance does not increase with drastic temperature changes (eliminating option 4). This leaves only option 3 available: There is less average global ice, and coral bleaching will occur.