The ratio of the activation energy of a chemical reaction to the universal gas constant is $1000 \mathrm{~K}$. The temperature-dependence of the reaction rate constant follows the collision theory. The ratio of the rate constant at $600 \mathrm{~K}$ to that at $400 \mathrm{~K}$ is
- $2.818$
- $4.323$
- $1.502$
- $1.000$