What were advantages of having a curtain wall castle?

In medieval castles, the area surrounded by a curtain wall, with or without towers, is known as the bailey. The outermost walls with their integrated bastions and wall towers together make up the enceinte or main defensive line enclosing the site. Curtain wall is an outer covering of a building in which the outer walls are non-structural. It keeps the weather out and the occupants in. As the curtain wall is non-structural entity, it can be made of a lightweight material reducing construction costs.

answer; (b) they could make more trips;

answer; (d) i believe that the correct answer is americans finally ran out of ammunition;