Why did the phrase "a cappella Sistina" ("in the style of the Sistine Chapel") eventually come to mean choral singing without instrumental accompaniment?

In this selection, the performing ensemble includes?

a. ?a takht ensemble featuring ‘ud and rebab. b. ?a zaffah procession band featuring bendir and nafir. c. ?mijwijz, nay, buzuq, qanun, voices, and percussion. d. ?Western chamber orchestra, percussion, and voices.

Which Baroque musician owes his modern reputation due to one of his works being selected as the theme music for the longest-running drama series in television history: Masterpiece Theater (now Masterpiece)?

a. Pachelbel b. Weelkes c. Vivaldi d. Mouret e. Purcell