Scientists often say that science is a cycle of "Experiment, fail, learn, repeat". Why is this an important concept in science and should this only apply in scientific research?

Because while doing research scientist follow the scientific metod.The scientific method involves exploration and observation and the search for the answer for a question. And there will always some hypotesis that while experimenting reveal to be wrong.

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.

the correct answer would be b. amelia, because the particals of gas move really fast (charged particals) and gas also has a lot of room (particals move independently) so the only answer that has both of those is amelia's.