Alice, Bob, and Charlie are each thinking of a number. Alice's number differs from Bob's number by 2. Bob's number differs from Charlie's number by 6. Charlie's number differs from Alice's number by N. What is the sum of all possible values for N?
<spanclass=′latex−bold′>(A)</span>4<spanclass=′latex−bold′>(B)</span>6<spanclass=′latex−bold′>(C)</span>7<spanclass=′latex−bold′>(D)</span>12<spanclass=′latex−bold′>(E)</span>14