Correct option is C ( $-\mathrm{E}_{\mathrm{a}} / 2.303 \mathrm{R}$)
Explanation:
The Arrhenius equation is:
$
\log _{10} \mathrm{k}=\log _{10} \mathrm{~A}-\frac{\mathrm{E}_{\mathrm{a}}}{2.303 \mathrm{RT}}
$
The y-intercept is $\log _{10} \mathrm{~A}$.
The slope is $\frac{-\mathrm{E}_{\mathrm{a}}}{2.303 \mathrm{R}}$.
Hence, option $\mathrm{C}$ is correct.