y = 3 x equation represents a proportional relationship.
Answer: Option B
Explanation:
A proportional variation represents a relationship between two variables x and y. It can be expressed in the form y=k x. Here, the ‘k’, the proportionality constant is equal to the slope m and the line goes through the origin
case A)

A linear equation that not passes through the origin and so not proportional variation
case B) y= 3 x
Is a linear equation but passes through the origin and so proportional variation
case C) y = - 3x+2
A linear equation that not passes through the origin and so not proportional variation
case D)

An inverse variation equation but not passes through the origin and so not proportional variation.
From these, equation option B is the proportion equation because in these equations, there is no addition and subtraction of any constant number. That’s why both these equations become proportional equations.