Which Grateful Dead album featured a side-long continuous improvisation?

One reason that performances by the Sun Ra Arkestra were distinct was

a. The use of standard instruments b. The use of elaborate costumes c. The use of a standard rhythm section d. The use of standard jazz forms

Siena and Florence are both located

a. in the Alps near France. b. in the Arno River valley. c. on the Tyrrhenian seacoast. d. in the region of Italy called Tuscany.