The energy of the incident photon is given by:
\[\frac{hc}{\lambda} = eV_s + \phi\]
Substitute the given values:
\[\frac{1240}{300} \, \text{eV} - 2.13 \, \text{eV} = eV_s\]
\[4.13 \, \text{eV} - 2.13 \, \text{eV} = eV_s\]
\[V_s = 2 \, \text{V}\]
Given below are two statements: one is labelled as Assertion (A) and the other one is labelled as Reason (R).
Assertion (A): Emission of electrons in the photoelectric effect can be suppressed by applying a sufficiently negative electron potential to the photoemissive substance.
Reason (R): A negative electric potential, which stops the emission of electrons from the surface of a photoemissive substance, varies linearly with the frequency of incident radiation.
In light of the above statements, choose the most appropriate answer from the options given below: