What is the grearest common factor of 56 and 92

We look for a number that can divide into 56 and 92 the same time.

2/    56      92              2 into 56 and 92
2/    28      46              2 again into 28 and 46
  /     14     23

There is no number that can go into 14 and 23 again so we stop.

Greatest Common Factor (GCF) =  2 * 2 = 4.

GCF = 4

A. is the answer in this question