Which specific iconographic element communicates hope in The Virgin of Carmel Saving Souls in Purgatory?

A musical structure in which the same melody is repeated over and over again with different treatment and without intervening new materials is a

A. fantasia B. symphony C. theme and variations D. rondo

Head arrangements were used in many big bands because

a. there were too many musicians involved to be completely spontaneous, so greater coordination was needed b. most of the musicians couldn't read music, so they never wrote anything down c. every tune has a head that needs to be arranged, unless it's played by a soloist d. band members could then take them and modify their parts to make them more interesting