Problem 23 (2015 AMC 8)

Tom has $12$ slips of paper which he wants to put into $5$ cups labeled A, B, C, D, E. He wants the sum of the numbers on the slips in each cup to be an integer. Furthermore, he wants the $5$ integers to be consecutive and increasing from A to E. The numbers on the papers are $2, 2, 2, 2.5, 2.5, 3, 3, 3, 3, 3.5, 4,$ and $4.5$. If a slip with $2$ goes into cup E and a slip with $3$ goes into cup B, then the slip with $3.5$ must go into what cup?