Given below are two statements: one is labeled as Assertion $A$ and the other is labeled as Reason $R$.
Assertion $A:$ Photodiodes are used in forward bias usually for measuring the light intensity.
Reason $R:$ For a $p-n$ junction diode, at applied voltage $V$, the current in the forward bias is more than the current in the reverse bias for $|V_z| > |V| \geq V_0$, where $V_0$ is the threshold voltage and $V_z$ is the breakdown voltage.
In the light of the above statements, choose the correct answer from the options given below.

• A
  Both $A$ and $R$ are true and $R$ is the correct explanation of $A$.
• B
  Both $A$ and $R$ are true but $R$ is $NOT$ the correct explanation of $A$.
• C
  $A$ is false but $R$ is true.
• D
  $A$ is true but $R$ is false.