You Are Measuring How Velocity Changes with Time of Two

You are measuring how velocity changes with time of two stars like the Sun in order to detect their planets. Both stars have a velocity curve with a periods of 2 years, but the maximum size (peak-to-peak amplitude) of the velocity curve of star A is 100 km/s, and for star B it is 200 km/s. What causes this difference? Assume the planets are named after their stars.

A) Planet A is less massive than Planet B.
B) Planet A is closer to Star A than Planet B is to Star B.
C) Planet A is more massive than Planet B.
D) Planet A is farther from Star A than Planet B is to Star B.
E) Not possible to say, since you're measuring the velocity curve of the stars, not the planets.