A feedback is a statement or an opinion that is directed
upon the input, so this is like an act of returning. In this case, a negative
feedback is something which sounds bad or terrible about the input. The
negative feedback from the choices is:
after you eat, glucagon stimulates an increase in blood
sugar levels
No one wants to have high blood sugar levels, so this is
negative.
A metaphor is a figure of speech that is used to make a comparison between two things that aren't alike but do have something in common. A metaphor uses this similarity to help the writer make a point: ... Her tears were a river flowing down her cheeks.