In the diagram, the numbers from 1 to 25 are to be arranged in the 5 by 5 grid so that each number, except 1 and 2, is the sum of two of its neighbours. (Numbers in the grid are neighbours if their squares touch along a side or at a corner. For example, the “1” has 8 neighbours.) Some of the numbers have already been filled in. Which number must replace the “?” when the grid is completed?
Answer Choices
A. 15
B. 12
C. 14
D. 11
E. 13