The major product of the following reaction is:

Methylcyclohexane reacts with Br$$_2$$/h$$\nu$$

When an alkene reacts with $$Br_2$$ in the presence of light ($$h\nu$$) or heat, the reaction proceeds via a free-radical mechanism that favors substitution at the allylic position.

The major product is formed by replacing the hydrogen atom at the most stable allylic position with a bromine atom. In this case, the carbon at the 3-position is both allylic and tertiary, making it the most reactive site.

Therefore, the hydrogen at the carbon at the 3-position is replaced by a Bromine atom.