D. It would be 30 C cooler, makes the most sense because greenhouse gasses cause warmth and without them it would get colder.
Growing willow for biofuel is sustainable development because it is a source of fuel which potentially will never run out. For every willow tree that is cut down, another can be planted in its place. This means that the source of fuel is potentially limitless and subsequently sustainable.
The costal cartilage connects the two together
The answer is whales. In the Antartic and Arctic regions, krills and whales are very abundant in numbers. Whales are number one consumer of krills in these regions. They can feed on a large swarm of krills when they feed. They also have less competition on these icy waters. They gain energy every time from eating them.