I'm having discussions on question 83 on the Part II exam: "The substitute must attempt the free throw(s) for a personal foul when the offended player must withdraw because of injury."

Some say the answer is false. The only way I see it false is if the team doesn't have any available substitutes. Anyone have an opinion?

This is true. The question implies that there is a substitute. If there is a substitute, that sub must shoot the shots.

All the question is saying is that, "If a player is fouled and injured, the sub for the player shoots the FTs." it's a TRUE statement.

In math terms the statement does more than imply that there is a substitute.
It says, "The substitute must..." Therefore, the substitute exists. It is a given within the statement.