Ais a system that uses vertical posts which are separated to support a horizontal beam.
a. truss
c. post-and-lintel
b. load-bearing
d. crenellation

A post-and-lintel is a system that uses vertical posts which are separated to support a horizontal beam. The answer is letter C. The horizontal beam is called the lintel and must not easily break. This type of system is mostly the basis of buildings nowadays.

the word that best describes martin luther king jr.'s tone in the video is dignified

martin luther king, jr. was a social activist and baptist minister who played a key role in the american civil rights movement from the mid-1950s until his assassination in 1968. the video shows his manner and attitude having or showing a composed or serious manner that is worthy of respect so dignified is the correct answer