Answer:

a. 135 :: 1+3+5 = 9 [divisible by 9]

b. 326 :: 3+2+6 = 11 [not divisible by 9]

c. 7893 :: 7+8+9+3 = 27 [divisible by 9]

6. 346 752 :: 3+4+6+7+5+2 = 27 [divisible by 9]

Explanation:

A number is divisible by 9 if the sum of its digits is divisible by 9.

Answer:

all of them are divisible by 9 except to the letter D