What is the primary function of a "metal-oxide-semiconductor field-effect transistor" (MOSFET) in electronic circuits?
A) A MOSFET controls the flow of electrical current in a circuit by varying the voltage applied to its gate, offering high efficiency and fast switching speeds.
B) A MOSFET measures the thermal output of electronic components.
C) A MOSFET filters out high-frequency noise from signals.
D) A MOSFET converts analog signals into digital form.