Final answer:
The correct statement indicating that the client understands how to use crutches safely is, "I'll use the handrails when going up and down stairs." This shows the client plans to utilize external support for added stability, reflecting an understanding of balance and crutch use principles.
Step-by-step explanation:
The client's understanding of the teaching can be identified when they make statements that align with safe and effective crutch use principles. When a person's leg is in a cast, using crutches correctly is crucial to maintain balance and prevent further injury. In this scenario, the correct statement indicating the client has understood the crutch use instructions given by the nurse would be:
"I'll use the handrails when going up and down stairs."
This statement reflects an understanding that stability and safety are increased when an external support, like handrails, is used in conjunction with crutches—particularly in potentially hazardous situations such as ascending or descending stairs. Placing the crutches under the arms and leaning forward, bearing weight on the injured leg, and keeping the crutches on the same side as the injured leg are not recommended practices and would indicate a lack of understanding of proper crutch use.