It's a very long sentence with a lot of information, but it is still only a simple sentence (option b): it has only one verb (taught). In order to qualify as a complex or compound-complex sentence, it would have to have at least 2 phrases, each with a different verb.
Terraces
^^^ would be the right answer.
Answer:
1. The style of fighting in America was much different than in Europe. Guerilla Warfare was popular among the American armies.
2. It is easier to supply your armies when you are fighting on your home turf. England had to load their supplies on ships while the colonists already had their supplies close to them.
Some other reasons:
The French.
British Arrogance.
Political Division in Great Britain.
