The easiest place to start is with the answer. The 3 by 4 rectangle (upper right) is the answer. P = 2(L + W) = 2(4 + 3) = 2*7 is 14.
14 is less than 16.
Now lets find out why the others can't be true.
The upper left has an area of 12 (6*2). So the area is find.
P = 2 * (L + W) = 2* (6 + 2) = 16 This would support the conjecture so it is not the answer you want.
The lower left has an area of 12 and a perimeter of 2*(12 + 1) = 26. That supports the conjecture. So you don't want that one either.
The lower right does not have an area of 12. It cannot help us at all.