Which of the sets shown includes the elements of set Z that are both odd numbers and multiples of 7?

Z = {−21, −14, −7, 0, 7, 14, 21}

A. {−21, 21}
B. {−21, −7, 7, 21}
C. {−14, 0, 14}
D. {−21, −14, −7}