Its B, I honestly dk how its B, it just is.
Answer:
Good music system and unique music.
Explanation:
Good music system and unique music makes a concert rock because in the concert the main thing is music. if music is not good either due to bad music system or bad music performed by singers, the people show no interest and they leave the concert. The people participate in the concert in order to hear good music so by making a concert good, they have to provide good music system and also good music.
Answer:
The volume of a cone is 1/3 that of a cylinder.
Explanation:
The volume of a cylinder is 
The volume of a cone is 
Therefore, the volume of a cone is 1/3 that of a cylinder.
