which graph shows a proportional relationship?

Explanation:

Step1: Recall proportional - relationship property

A proportional relationship has the form $y = kx$ ($k\neq0$) and its graph is a straight - line passing through the origin $(0,0)$.

Step2: Analyze each graph

• The first graph does not pass through the origin.
• The second graph is a non - proportional linear relationship (a line with a non - zero y - intercept).
• The third graph is a straight line passing through the origin, which represents a proportional relationship.
• The fourth graph is a horizontal line, which is not a proportional relationship.

Answer:

The third graph.