For purposes of lie detection,investigators have most commonly made use of a(n)

A) electrocardiograph.
B) electroencephalograph.
C) myograph.
D) polygraph.

The polygraph, also known as a lie detector test, is the most commonly used tool for lie detection by investigators. It measures physiological changes such as heart rate, blood pressure, and breathing patterns, which can indicate when a person is lying or being deceptive. However, its accuracy and reliability have been widely debated and questioned by experts in the field.