Final answer:
According to Rule 6.3c(2) in golf, if a player's ball is played by another player as a wrong ball, no penalty is incurred and both players must continue playing with their correct balls, replacing them where necessary.
Step-by-step explanation:
If a player's ball was played by another player as the wrong ball under Rule 6.3c(2) of the Rules of Golf, the correct action to take is that the player incurs no penalty, and both players must continue play with the correct balls. Specifically, the rule states that the player must replace his or her ball on the original spot (which if not known must be estimated) to the extent possible and play it from there. The mistake of playing the wrong ball must be corrected before the player makes a stroke at the next hole.