A 15-foot ladder is leaning against a wall. The base of the ladder is 9 feet away from the wall. How high up the wall does the ladder reach?

✓ Correct Answer: Option B

This forms a right triangle. Using the Pythagorean theorem (a² + b² = c²), where c=15 (ladder) and a=9 (base), we have 9² + b² = 15². So, 81 + b² = 225. Subtracting 81 gives b² = 144, so b = 12 feet.