(C)
Wrong. Although infinite acceleration is impossible, requiring infinite forces and crushing all macroscopic objects, reasonable accelerations over a period of time can produce incredible speeds. In fact, speeds approaching the speed of light can be achieved in less than one year with accelerations less than one g. Higher accelerations can achieve relativistic speeds in even less time. Therefore, by extending the time and distance of the constant velocity phase of the trip to larger and larger amounts, the acceleration phase of a trip can be made negligibly small. Consequently, neglecting the acceleration phase of the trip in no way invalidates the spaceship’s viewpoint or alters the conclusions. It only simplifies the argument.