Direct variation means that x and y will always have the same ratio. The only function that does that is the first one y = 0.3x.
For example: (1, 0.3), (2, 0.6), (3, 0.9)
These are the first three points of the function. The ratios 1/0.3, 2/0.6, and 3/0.9 are all the same when you reduce them.
