Final answer:
The velocity change of the star, as measured by the Radial Velocity (Doppler) method, reflects the planet's mass and orbital distance. The technique observes the Doppler shifts in the star's spectrum to infer these characteristics.
Step-by-step explanation:
When a planet is detected via the Radial Velocity (Doppler) technique, the velocity change of the star is a measure of B) the planet's mass and orbital distance. The radical velocity change is due to the gravitational influence of an orbiting planet causing the star to wobble.
This wobble is manifested as tiny but measureable Doppler shifts in the spectrum of the star—redshift when the star moves away and blueshift when it approaches. By analyzing these shifts, astronomers can deduce the planet's mass and its period of orbit around the star.
However, the Doppler technique does not provide direct measurements of the planet's radius or composition; these require additional methods such as the transit technique.