Question

Suppose that A is the set of sophomores at your school and B is the set of students in discrete mathematics at your school. Express each of the following sets in terms of A and B.

a) the set of sophomores taking discrete mathematics at your school
b) the set of sophomores at your school who are not taking discrete mathematics
c) the set of students at your school who either are sophomores or are taking discrete mathematics
d) the set of students at your school who either are not sophomores or are not taking discrete mathematics

I am not sure which is union/intersection/difference.