The two main architectural systems of frame construction are the skeleton and the post-and lintel. These systems are crucial for constructing stable and flexible structures. The best answer from the provided choices is option a. ;
The two main architectural systems of frame construction are the skeleton and the post-and lintel. The skeleton system allows for flexible designs, while the post-and-lintel system is one of the oldest methods used in architecture. Therefore, the best answer is option a.
;