Let x={x|x is a whole number less than 15}, y={x|x is multiple of 3 less than 15}, z={x|x is a real number greater than or equal to 5.5}

What is xny?

A. 0,3,6,9,12

B. 3,6,9,12,15

C. -6,-3,0,3,6,9

D. -6,-3,0,3,6,9,12