The opposite sides of a parallelogram are parallel to each other. So since side NM lies on the x axis, side KL must be parallel to the x axis.
Therefore all points on side KL are the same distance from the x axis, meaning that if L is 3 above the x axis, b = 3, and K is also 3 above the x axis.
area of a parallelogram = base x height
Since all points on KL are 3 above the x axis, on which NM lies, the height of the parallelogram is 3.
Meanwhile, since the y coordinates for K and L are the same, the length of KL is simply the change in x. So KL is 2 long.
So using KL as the base, we get area = 2 x 3 = 6.
The correct answer is B.