The graph shows the costs of purchasing two types of flowers.
Select some value
for x and draw vertical line

This line intersects the graphs of Flower A and the graph of Flower B in points A and B, respectively. The point A lies on this vertical line higher than the point B. This means that y-coordinate of point A is greater than y-coordinate of point B.
If y-coordinate of point A is greater than y-coordinate of point B, then Flower A is more expensive than Flower B (or Flower B is less expensive than Flower A).
Answer: correct choice is B