Answer :
well, the area of a parallelogram is simply A = bh.
we know that "b" and "h" are whole numbers or namely integers, and we know the area is 6, doing a quick prime factoring of 6 we simply get
6 = 2 * 3
2 and 3 are both prime, in how many ways can we arrange them? just 2 and 3 or 3 and 2, so those are the only possible values for "b" and "h".