Which of the following do you use to tell whether a relationship is
proportional or not?

The correct option to tell whether a relationship is proportional or not is;

Step-by-step explanation:

A proportional relationship is a relationship between two variables, 'x', and 'y' such that they have equivalent ratio, such that all values of variable 'y' are given by the product of the values of the variable 'x' and a constant, 'k'

Therefore, y = k · x, from which we have;

Therefore we can use to tell whether a relationship is proportional or not proportional.