Respuesta :
Factors of 51: 1, 3, 17, 51
Factors of 68: 1, 2, 4, 17, 34, 68
As you can see the greatest common factor of both numbers is 17.
Therefore, the answer is C.
Best of Luck!
the answer is C, 17. The factors of 51 are 1,3, and 17. The factors of 68 are 1,2,4,17, and 34. 17 is the GREATEST common factor