The correct option is C {3,6,9,12}
3, 6, 9 and 12 are the natural numbers that are less than 15, and are divisible by 3.
In roster form, the elements of the set are listed within a pair of braces, and are separated by commas.
Thus, the set of natural numbers less than 15 and divisible by 3 in roster form is given by {3,6,9,12}.