A pulse taken on the wrist, just below the thumb, is known as a:

The designation of the pulse taken on the wrist just below the thumb as the radial pulse is accurate because the radial artery runs along the radial side (thumb side) of the forearm and is easily accessible at the wrist. This location is commonly used to assess heart rate due to its convenient positioning and because it offers a clear indication of circulatory health.

In contrast, the carotid pulse is found in the neck along the carotid artery, the brachial pulse is located in the upper arm near the elbow, and the femoral pulse is detectable in the groin area through the femoral artery. The specific anatomical locations of these arteries are what distinguish the pulses, making the radial pulse the most relevant option for a pulse measurement in that location.