Answer:
high frequency sound waves
Explanation:
The fetal cardiac activity emits signal that comprises of high frequency sound waves. This signal is received only when it is converted into a fetal heart rate tracing via computer. These signals are traced through transducers and are shown on the external monitor.
The answer for this question is:
(C) U.S. Metric System
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The joining of an egg and a sperm
A mood and sensory altering drug.
