Gianina PLEASE

Which number can be used as a counter example to, "Any number that is divisible by 3 is divisible by 9"? a)9, b)18, c)30, d)40 Can you explain me the answer how do you get it? because I don't understand about counter examples. Thanks

A repeating decimal is _____ a rational number. a) always; b) sometimes; c) never