Question

In which of the following case, do the quantities vary directly with each other?

Options:

(a)

x	0.5	2	8	32
y	2	8	32	128

(b)

p	`1^2`	`2^2`	`3^2`	`4^2`
q	`1^3`	`2^3`	`3^3`	`4^3`

(c)

r	2	5	10	25	50
s	25	10	5	2	0.5

(d)

u	2	4	6	9	12
v	18	9	6	4	3