In a simple series regulator circuit, which of the following components is the controlling element?

In a simple series regulator circuit, which of the following component

1.	In a simple series regulator circuit, which of the following components is the controlling element?
A.	Load resistor
B.	Zener diode
C.	Transistor Q
D.	<sub>1</sub>
E.	None of the above
Answer» D. <sub>1</sub>