Final answer:
To take an apical pulse, a nurse would need a stethoscope, as it allows them to listen directly to the heartbeats and measure their frequency.
Step-by-step explanation:
When a nurse is taking an apical pulse, the equipment needed is a stethoscope. This instrument allows the nurse to listen to the heartbeat directly and measure the number of heartbeats per minute. Unlike taking blood pressure with a sphygmomanometer, which also involves a stethoscope to listen to Korotkoff sounds, the apical pulse requires the clinician to place the stethoscope at the apex of the heart. The stethoscope is essential for this task, as it amplifies the sounds of the heart, enabling the nurse to count the beats accurately.