Here are the factors of 60:
1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60
If you want to include negative values, then this list would be included
-1, -2, -3, -4, -5, -6, -10, -12, -15, -20, -30, -60
So whatever list of answer choices you are given, simply pick the value that hasn't been mentioned so far. For example, if 8 is one of the answer choices, then this would not be a factor of 60.
A test of this is to divide 60 over 8 to get 60/8 = 7.5, which is not a whole number. In contrast, something like 12 is a factor of 60 because 60/12 = 5 is a whole number.
