Given below are two statements. One is labelled as Assertion (A) and the other is labelled as reason (R).

Work function is characteristic to a metal. It is independent of incident radiation's energy/frequency.

$W=h{\gamma }_0\Rightarrow W\propto {\gamma }_0\propto \frac{1}{{\lambda }_0}$. It implies threshold frequency and threshold wavelength indeed depend on the nature of the metal.