Final answer:
For taking an infant's pulse, the brachial artery is the most appropriate site for an EKG tech, but the apical pulse using a stethoscope is also a reliable method.
Step-by-step explanation:
The most appropriate site for an EKG tech to use when taking the pulse of an infant is the brachial artery. Although the pulse can be measured at any accessible artery, such as the radial or carotid arteries, in infants, the brachial artery is often preferred due to its size and proximity to the surface in the upper arm. Moreover, the apical pulse, detected via auscultation with a stethoscope, is another reliable way to assess heart rate in infants, and it is particularly useful for detecting murmurs or other heart sounds that are difficult to find through palpation of peripheral arteries.