Equation of y-axis is considered as

As y-axis lies on xy plane and yz.

So its distance from xy and yz plane is 0.

∴ By basic definition of 3-D coordinate we can say that x-coordinate and z–coordinate are 0.

∴ any point on Y-axis has x and z coordinate = 0

∴ x = 0 and z = 0 can be considered as the equation of y-axis.

Hence, option(C) is the only correct choice.