The slope of Arrhenius Plot ($\ln k$ vs $1/T$) of first order reaction is $-5\times 10^3\text{K}$. The value of $E_a$ of the reaction is: [Given $R=8.314{\text{J K}}^{-1}{\text{mol}}^{-1}$ ]

1. A
   $166{\text{kJ mol}}^{-1}$
2. B
   $-83{\text{kJ mol}}^{-1}$
3. C
   $41.5{\text{kJ mol}}^{-1}$
4. D
   $83.0{\text{kJ mol}}^{-1}$