The correct option is D Rectilinear and rotational
The observer is inside the bus and flipped the coin in the upward direction. While going upwards, the coin undergoes two types of motion.
The coin is moving upwards and follows a straight line. Therefore, the coin has a rectilinear motion.
The coin is also rotating about its own axis. Therefore, the coin is experiencing a rotational motion while moving in a straight line.
So, a coin flipped upwards has a combined motion: Rectilinear and rotational.