Nitrogen dioxide gas is dark brown in color and remains in equilibrium with dinitrogen tetroxide gas, which is colorless. (g) ⇌(g)

When the mixture was moved from room temperature to a higher temperature, the mixture turned darker brown. Which of the following conclusions about the mixture is true?

A. The forward reaction is exothermic.
B. The backward reaction has a negative net enthalpy.
C. The colorless gas has a higher enthalpy than the brown gas.

I know that is an exothermic reaction, but it shifts to left, so it should be a backward reaction, not a forward. Therefore, I don't think it is A. I am leaning towards B, but I would like someone to double-check my thinking. Please no fake answers or external links. Thanks in advance!