Final answer:
The equation y = 2x represents a direct variation.
Step-by-step explanation:
A direct variation is a relationship between two variables where one variable is a constant multiple of the other. In other words, as one variable increases or decreases, the other variable also increases or decreases proportionally. The equation that represents a direct variation is of the form y = kx, where k is the constant of variation.
Out of the given options, the equation y = 2x represents a direct variation because it follows the form y = kx, where k = 2.