I feel B is the complex, compound sentence... I regret I cannot tell you why.
The three forbidden things are:
1. It is forbidden to go East.
2.It is forbidden to go to the "Dead Places", unless you're a priest searching for metal.
3. It is forbidden to cross the great river and look at the "Palace of the Gods".
So option B. To go alone is not forbidden.
Hope it helps!
C. By limiting the amount of coverage any one topic gets