Questions: People who graduate from that school

The answer is "People who graduate from that school."

This is the major class in the argument. The statement "Everyone who graduates from that school gets a great job" establishes this group as the major class from which the argument reasons down to Bob.

This is a specific subset of the major class, but it is not the major class itself. The argument specifies Bob as a member of this group, but it is not the primary category from which the conclusion is drawn.

This is the outcome or conclusion of the argument, not the major class. The argument concludes that Bob will be part of this group based on his membership in the major class.