In Bach's Gigue from Cello Suite No.2 in D Minor:
A) an a section is in duple meter, and a b section is in triple meter.
B) an a section is unaccompanied, and a b section is accompanied by the continuo.
C) an a section is repeated, and a b section is repeated.
D) an a section opens with a fugue, and a b section is somber.