The potential difference that must be applied to stop the fastest photo electrons emitted by a nickel surface, having work function $5.01\text{ eV}$, when ultraviolet light of $200\text{ nm}$ falls on it, must be:

1. A
   $1.2\text{ V}$
2. B
   $2.4\text{ V}$
3. C
   $-1.2\text{ V}$
4. D
   $-2.4\text{ V}$