What Type of Search Technique Has Discovered the Second Largest

What type of search technique has discovered the second 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 excess infrared radiation from the star, caused by the presence of planets that are cool and thus emitting primarily in the infrared
D) using space-based telescopes to search for tiny pinpoints of light that follow circular or elliptical paths around the star