The two main architectural systems of frame construction are
a. the skeleton and the post-and lintel.
b. the materials and the truss.
c. the design and the architect.
d. the shell and the skeleton.

I believe the answer is: d. the shell and the skeleton

The shell and skeleton in architecture would act as the main foundation that support the weight of the whole building. The strength of shell skeleton would determine whether the building would collapse during natural disaster such as earthquakes.

answer; /// representative democracy restricting trade,is your correct answer;

the correct answer is ) possibility.

demonstrating opportunity cost is done through production possibility.

the opportunity cost can be demonstrated using the production possibility frontier or curve. this graphic shows the total number of possibilities for two products when we have the resources needed and used in an efficient manner. the main resources could be money, labor, and technology. the curve shows that the production of one good increases when the production of the othe