Hopefully this will help you a little bit
Answer:
When people put their money in the bank to save it other people can borrow that money. As they pay it back you won't loose money and the bank will earn in interest. So as long as people are putting their money into the bank others will be able to borrow when tight on money. This is similar to herd immunity because as long as a greater number are doing it the minority that can't will be protected.
She was kind of mysterious at the beginning but through the play she became less mysterious.
I think that C, that is, "they found the charge and trouble very great, and they had little or no crop it is not doubted", is your answer.
Understatement represents something as smaller or less intense than it reallly is, it presents it as less important. In sentence C, the speaker refers to a problem as a minor inconvinience "(...)trouble very great". Generarlly, we all know, that troubles are far from great. "They had little or no crop it is not doubted", you could change the focus and say that you have "some crop" instead of referring to the crop as being little.