premise: A summer program offers at least one of the following seven courses: geography, history, literature, mathematics, psychology, sociology, zoology. The following restrictions on the program must apply: If mathematics is offered, then either literature or sociology (but not both) is offered. If literature is offered, then geography is also offered but psychology is not. If sociology is offered, then psychology is also offered but zoology is not. If geography is offered, then both history and zoology are also offered. If the summer program offers mathematics, then which one of the following must be true?
hypothesis: At least three courses are offered.