The greatest common factor of 16 and the positive integer n is 4, and the greatest common factor of n and 45 is 3. Which of the following could be the greatest common factor of n and 210?

3

14

30

42

70

OA 42

The explanation states that a 7 but not a 5 could be a common factor. Can someone please explain this. I don't see how 7 is a common factor.