They are saying represent in "P if and only if Q" form. Actually double implications are commutative so "P if and only if Q" is same as "Q if and only if P".
A. You get an A in this course if and only if you learn how to solve discrete mathematics problems.
B. You will be informed if and only if you read the newspaper every day.
C. It rains if and only it is a weekend day.
D. You can see the wizard if and only if he is not in.