A planetary gear train is gear train having
(a) A relative motion of axes and the axis of at least one of the gears also moves relative to the frame
(b) No relative motion of axes and no relative motion of axes with respect to the frame
(c) No relative motion of axes and the axis of at least one of the gears also moves relative to the frame
(d) A relative motion of axes and none of the axes of gears has relative motion with the frame