2. Give recursive definitions of the following sets. (Remember to include a basis step and a recursive step, and to give a brief justification why your definition works.) (a) ( 3 points) The set of all multiples of 6. (b) (3 points) The set of all binary strings of the form 11 . . . 1 | {z } n 00 . . . 0 | {z } n for any positive integer n. (c) (3 points) The set of all fractions of the form 1/2 n for any positive integer n