The answer is I. But when I make a model of the double bonded molecule, the methyl group and hydrogen are equatorial. Yet when an addition reaction occurs, why/how does the hydrogen change from its equatorial position to an axial position?
If I take apart the model and turn it into hexane, the methyl and hydrogen are still both equatorial and the new groups are both axial, so it can't just be the change in conformation from a chair forming.