I completed 3/4 of the answers, by choosing the correct reaction pathways leading to each of the 3 different products. But I don't know how to draw the reactant diene, I really thought what I initially had was correct, should I make a trans reactant or is there something else missing?
Do we agree that the first step ist the addition of a proton to the diene? This is bit different from the addition of HCl to an alkene, where you would rely on the Markovnikov rule.
Here, stabilization of the cation through resonance comes into play.
I don't know how to draw it [...]
In principle, a proton could add to one of the positions a to d.
How do the resulting cations look like and which of them are stabilized by resonance?
Is it now a bit more clear?