Final answer:
Without context on the specific game, it's not possible to provide an accurate answer; however, in several games, both the original or a different ball can be used to replace a ball on a spot.
Step-by-step explanation:
The question posed doesn't neatly fall under a specific academic subject but it seems to be related to rules in a game, possibly snooker, billiards, or another game that involves placing a ball on a spot. Accordingly, the correct answer could vary depending on the specific game's rules in question. The question seems to be part of a multiple-choice exercise about understanding rules and game play. In many games, the rules allow for both a) the original ball or b) another ball to be used when replacing a ball on a spot, so c) both a and b could be the right answer. Without further context about the specific game and its rules, a definitive answer cannot be provided.