Carlos is arranging books on shelves. He has 24 novels and 16 autobiographies. Each shelf will have the same numbers of novels and autobiographies. If Carlos must place all of the books on shelves, what are the possible numbers of shelves Carlos will use?
1, 2, 4 or 8 shelves
1, 2,4 or 6 shelves
1, 2, or 4 shelves
2, 4, 6, or 8 shelves