What is as light as a feather but only a man can hold for 45-50 seconds?

What role do background vocalists play? a. they provide additional support to the main vocalist and other members of a music group during recording sessions and live events. b. they perform as part of orchestras working for music theaters. c. they mix different songs or music scores and present a unique blend of music to an audience. d. they assemble and organize musical compositions according to their clients’ requirements.