It's better to get a laptop. They would ask you to turn your computer around and even below your desk to check the environment. Besides, it's not a good idea to burden yourself with things like computer before such an important exam.

Only about 1 person in 30 can score 170+. It's good to have it as a target, but failing to achieve so doesn't constitute any reason at all not to value your own efforts.

Focus on yourself and your own problem. Only by removing your own obstacle, you can improve. Analyzing the questions what you did wrong would be pretty effective in realizing your weakness.

Good luck on your journey.

I think the last paragraph is really just qualifying the paragraph before it. Showing that major eruptions can only cause a mild temperature drop globally doesn't deny the possibility that the loop may magnify even a small drop locally. So really, it only denies the connection rather than establishing a relation to the contrary.

Turmeric is just one of the basic ingredients of curry. Without E, the argument in the stem is insufficient. Because it overlooks the possibility that it's something else, rather than the Turmeric that is helping people. E provided a stronger bridge between Curry and Turmeric, extending the positive correlation between Cognitive Function and Eating Curry to actually eating Turmeric.

I guess that might better explain why E is the right choice.