If 9 parallel lines in a plane is intersected by a family of another 8 parallel lines, how many parallelograms are there in the network thus formed?  Pick one
A) 80  B) 63  C) 120  D) 1008  E) 1260

Rationale: "parallelogram can formed by 2 horizontal and 2 vertical lines for horizontal 9 c 2 for vertical 8 c 2 total parallelogram is 9 c 2 * 8 c 2 = 36 * 28 = 1008 answer : d"
Answer: D