The graph on the right.
Work Step by Step
For the graph on the right, January has a point at 40, which is on the fourth horizontal line. The point for June is at 50 (on the fifth horizontal line). The graph appears to have increased 25% in six months (4∗1=5), and, this did happen ($50−40=10$, and $10/40=.25$). The graph on the left has a graph where the price appears to have doubled, but we know this didn't happen.