How many numbers from 10 to 31 are exactly divisible by 3? Choose the correct choice from the following choices:
A) 13 B) 15 C) 16 D) 7 E) 18

Rationale: "12 , 15 , 18 , 21 , 24 , 27 , 30 . 7 numbers . 10 / 3 = 3 and 31 / 3 = 10 = = > 10 - 3 = 7 . therefore 7 digits d )"
Answer: D