Suppose You Are Using the Doppler Technique to Look for Planets

Multiple Choice

Suppose you are using the Doppler technique to look for planets around another star.What must you do?

A) Compare many spectra of an orbiting planet taken over a period of many months or years.
B) Compare the brightness of the star over a period of many months or years.
C) Carefully examine a single spectrum of an orbiting planet.
D) Compare many spectra of the star taken over a period of many months or years.