How Have Astronomers Learned What Different Asteroids Are Made Of

Multiple Choice

How have astronomers learned what different asteroids are made of?

A) The only way is to send a spacecraft to each asteroid and bring a chunk of it home
B) They measure the x-rays that all asteroids give off
C) They wait until the asteroid has a tail of gas behind it and measure that tail
D) They examine the spectrum of the sunlight that reflects from the asteroid
E) There is no way at the present time to know what asteroids are made of