Final answer:
There is no penalty for the accidental deflection by the caddie, but the player must take relief under the penalty area Rule (17.1d) and cannot simply move the golf bag.
Step-by-step explanation:
The correct ruling for the scenario where a player's caddie accidentally deflects the player's ball after a stroke and it comes to rest in a penalty area on the player's golf bag is that there is no penalty for the accidental deflection. However, the player must take relief under the penalty area Rule (17.1d). This means that although there is no penalty for the accidental deflection by the caddie, the player cannot move the bag (the movable obstruction) to gain an advantage as the ball lies in a penalty area.
The player must either play the ball as it lies or take relief with a one-stroke penalty under Rule 17.1d. This rule is designed to ensure fair play and maintain the challenge of playing the ball from a penalty area.