What Type of Search Technique Has Discovered the Largest Number

Multiple Choice

What type of search technique has discovered the largest number of planets around stars other than the Sun?

A) looking for tiny variations in the star's position in the sky, caused by the gravitational pull of one or more planets orbiting the star
B) looking for tiny variations in the star's radial velocity, caused by the gravitational pull of one or more planets orbiting the star
C) looking for tiny variations in the star's brightness, caused by the planet moving in front of the star
D) using space-based telescopes to search for tiny pinpoints of light that follow circular or elliptical paths around the star