Open the UNL radial velocity simulator: https://astro.unl.edu/naap/esp/animations/radialVelocitySimulator.html It is extremely hard to detect a planet orbiting a star so astronomers must look at the motion of the star the planet orbits and its wobble will determine the motion and size of planet orbiting it. Run the simulation and match the positions on the planet's orbit (1-4) with the letters (A, B, C ,D) corresponding to the labeled positions of the radial velocity curve. Hint: the radial velocity in the plot is still that of the star, so for each of the planet positions determine where the star would be and in which direction it would be moving. You may want to slow down the animation speed for this