The mean free path of electrons in a metal is $4\times10^-8$ m. The electric field which can give on an average 2 eV energy to an electron in the metal will be in units of V/m :

Question

( A ) $8\times10^{-11}$
( B ) $5\times10^7$
( C ) $8\times10^7$
( D ) $5\times10^{-11}$