you have to think of certain characteristics as appearing AT MOST once in each row and column. One characteristic is parallel horizontal lines. We can see those are already at b1, c2 and a3. So we can assume the figure wont have parallel horizontal lines, which rules out A, B and F. Another characteristic is an upward arrow. These are at c1, a2, and b3, so we can rule out C. This leaves D and M. From D and M we can rule out that we should look for downward arrows since they both have these. We can also rule out looking for parallel vertical lines as they both have these as well. We can rule out E because that would cause a single horizontal line to appear more than one in column c. As a corollary we can see that representation of vertical parallel lines is desired both in column c and row 3. Therefore the answer is D.