Final answer:
The nurse should position the client's leg at heart level when measuring blood pressure in the lower extremity.
Step-by-step explanation:
The nurse should d) position the client's leg at heart level when measuring blood pressure in the lower extremity. The standard method for measuring blood pressure is to use a cuff on the upper arm at the same level as the heart. Placing the cuff above the ankle in the lower extremity would not provide accurate results. Positioning the client's leg at heart level ensures that the blood pressure measurement is taken at the appropriate height relative to the heart.