Can you please Solve for a I keep geting the problem wrong and I dont understand how to fix it

Linux is distributed under gnu gpl. why is this important? a. it ensures that only torvalds can profit from the sale of linux b. it prevents unknowledgeable users from downloading programs they don't know how to operate. c. it provides protection for the developers who created linux. d. it states that anyone can copy, modify, and share the program if changes are made public.

Acase study allows a more detailed look at the life of a single subject than any other study.

Me and category do i put them in because this is science