Marcus sorts his 85 baseball cards into stack of 9 cards each. how many stacks of 9 cards can marcus make?

The answer is 9 stacks.

As the number of cards in each stack is nine, you should divide the total amount of cards by nine. So it should be 85/9 = 9.4. As you can't divide a card into its fourth part, Marcus would have 9 whole stacks and 4 cards that would not belong to any stack because 9x9 = 81 and the total amount of cards (85) minus the amount of cards in stacks (81) is 4.

are their choices tho?

first one is your answer

~coco