The voltage gain of the following amplifier is

Given below are two statements:
Statement $I$: Photovoltaic devices can convert optical radiation into electricity.
Statement $II$: Zener diode is designed to operate under reverse bias in the breakdown region.
In the light of the above statements,choose the most appropriate answer from the options given below:

In which of the following circuits is the junction reverse biased?

In which of the following cases is the junction diode $NOT$ in reverse bias?

In which of the following circuits is the diode in reverse bias?

Find the value of current $I$ in the following circuits.