Math
posted by Bob .
Which group names all the whole number factors of a composite number?
A) 2,3,12,24
B) 1,5,10
C) 1,3,5,15
D) 1,31

not A, since 6 is not included
not B, since 2 is not included
not D, since 31 is prime
C 
Not sure if "a composite number" is meant to be the largest composite number of each group. If this is so, then check the factors of the largest number of each group to see if they are all named. For example, the factors of 31 are 1 and 31. So all integer factors are named.
There are two choices where all factors are named, and the other two name all the factors (like D).
However, only one of the choices contains a "composite number" as the largest number, i.e. not a prime.
Can you find it?