What Technique Did Astronomers Use to Make the First Confirmed

Multiple Choice

What technique did astronomers use to make the first confirmed discovery of a planet around another star like the Sun?

A) block out the light of the star and take a photograph of the fainter planet
B) measure the position of the star on the sky very carefully over many years and search for small wiggles in its position due to the gravitational pull of a planet
C) measure the Doppler shift of the lines in the star's spectrum and look for periodic changes in this shift due to the pull of the planet as it orbits the star
D) search for the presence of metallic and rocky elements in the spectrum of the star
E) look for a small dip in the light of the star when the planet crosses its disk