The First Technique That Allowed Astronomers to Find Exoplanets Involved

Multiple Choice

The first technique that allowed astronomers to find exoplanets involved:

A) photographing the planets using infrared waves
B) looking for the decrease of light from the star during a transit of the planet across its disk
C) sending a very small spacecraft to the exoplanet to take close-up images
D) measuring changes in the radial velocity (Doppler shift) of the star caused by the pull of orbiting planets
E) simply taking a visible light photo of the planet around the nearest star; it wasn't that hard