The correct option is C 310
511:
Let's rewrite the numerator and the denominator into its factors
Factors of 5:1–,5
Factors of 11:1–,11
511 is in the simplest form, because 5 and 11 have no common factors other than 1.
510:
Let's rewrite the numerator and the denominator into its factors
Factors of 5:1–,5–
Factors of 10:1–,2,5–,10
511 is not in the simplest form, because 5 and 10 share common factors of 1 and 5.
310:
Let's rewrite the numerator and the denominator into its factors
Factors of 3:1–,3
Factors of 10:1–,2,5,10
310 is in the simplest form, because 3 and 10 have no common factors other than 1.
39:
Let's rewrite the numerator and the denominator into its factors
Factors of 3:1,3
Factors of 9:1,3,9
39 is not in the simplest form, because 3 and 9 share common factors of 1 and 3.