Are you certain you haven't learned E2 eliminations? It doesn't seem like you could answer this question without knowing eliminations.
Yes, you can look at dehydrations as backwards hydrations. That might help you answer this question. Starting with the given alkene, add H3O+ and see what products are possible. That should point you in the right direction.
nj_bartel and zanethan are right, you just need to put the pieces together. No, it's not a diol.