Final answer:
The last sounds understood in blood pressure measurement are thumping sounds, indicating the diastolic pressure when the blood flow becomes silent in the artery, marked by the disappearance of Korotkoff sounds.
Step-by-step explanation:
The sounds heard during the last phase of blood-pressure measurement are D. thumping sounds. As more air is released from the sphygmomanometer cuff, blood flow through the vessels becomes silent as it flows freely through the brachial artery. This silent phase corresponds to diastolic pressure, which is the lower figure in a blood pressure reading.
The disappearance of the Korotkoff sounds marks the diastolic pressure level, and no further sounds are heard beyond this point. Murmurs, on the other hand, are unrelated to blood pressure measurement and are unusual heart sounds caused by turbulent blood flow.