For a circular orbit, orbital velocity v = sqrt(GM_star/a), which depends only on the central star's mass and orbital radius a -- NOT on the orbiting planet's own mass -- so a planet at 4 times the distance orbits at half (1/sqrt(4)) the speed of a closer planet.
Orbital velocity for a circular orbit is v = sqrt(GM_star/a), independent of the orbiting planet's own mass. Comparing planet B (at distance 4d) to planet...
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