Which of the following sets of factors do 64 and 28 have in common?
{1, 2, 4}
Explanation
The factors of 64 are {1, 2, 4, 8, 16, 32, 64} and the factors of 28 are {1, 2, 4, 7, 14, 28} making {1, 2, 4} the set of factors that 64 and 28 have in common.