The answer should be "slow" the first pairing both end in "-est" making them superlatives giving a parallel in the structure. Following the same structure, the words from the pairing after can be ignored, the word dim is an adjective, "light" bulb is a noun, therefore, it is not a parallel structure.
Coloring different countries different color is good because you would memorize the colors and it wouldn’t have to take a long time for you to find the countries you’re looking for. Idk if this makes sense but ye
I agree with you on #1.
#2 is make use of his skills in surgery. You want to prove that dispensary has something to do with medicine. Children at an orphanage doesn't include medicine. Anatomy at the medical college puts the medicine in a different place than the dispensary.
Question 1: D. If something is cavernous, that means that it has a large cavity in it. However, according to the context in the question you posted, the best answer would be ‘a large and dark space.’
Question 2: C. A paradox is something that contradicts itself. For example, if I travelled back in time and killed my mother before she met my father, she would never give birth to me. However, that would mean that I would never have an opportunity to go back in time and kill my mother, because I wouldn’t exist. So, my mother would be alive, which means I would be alive, which means I could travel back in time to kill her, which means she would be dead- and on and on.
Question 3: I’m not sure about the answer for this one. Synchronization is harmony, or movement at the same time; for example, I want to achieve synchronization in my cheering routine with the rest of my teammates- this means that we would perform the cheering routine at the same time, in harmony with each other. The answer is probably C or D.