1. A classical nova is
A. a gigantic thermonuclear explosion that consumes an entire star.
B. a thermonuclear runaway that occurs on the surface of a white dwarf.
C. an event that releases much more energy than a Type Ia supernova.
D. the formation of a new star.
E. All of the above.
2. A standard candle
A. is an object that is the brightest of its class.
B. means that an object is not very bright.
C. is a standard unit of distance in astronomy.
D. is something that can always be expected to have about the same brightness.