Question

which is an example of joint variation?
A) x 3 2 4 11
y 8 9 6 7
z 16 27 12 28

B) x 2 -2 6 -6
y 3 -3 7 -7
z 4 -4 8 -8

c) x 4 6 3 5
y 9 8 6 12
z 24 32 12 40

d) x 9 8 7 9
y 10 7 5 8
z 450 180 225 360

all answers are supposed to be in a table