Solution:
Meaning of Direct Variation:
Two quantities vary directly if two of them are directly proportional to each other.
For example : equation of any line passing through origin is an example of direct variation.
Their equation is given by : 1. x = k y or 2. y = k x where k is constant of variation.
Out of the options given : 1. y = 2 x
2. y = x are examples of direct Variation.