professional tennis players must focus despite any number of distractions, for example, a sharp ray of light…

Brief Explanations:

• The original phrase "spectator's watch's" is incorrect.
• Option B "spectator's watches" changes the meaning as it implies multiple watches per spectator which is not the case.
• Option C "spectators watch's" has incorrect possessive form for "spectators".
• Option D "spectators' watch's" is also incorrect as it should be "spectator's watch" (singular spectator, singular watch).
• The correct form is "spectator's watch" (possessive of a singular noun). But since the options don't have that exact correct form (assuming it's a typo in the problem setup and we are to choose from given), the original "NO CHANGE" (Option A) is wrong. But if we consider the intended meaning of a single spectator's single watch, the closest among the given options (if we assume a mis - optioning) is Option A (though grammatically it should be "spectator's watch" without the second apostrophe - perhaps a formatting error in the problem).

Answer:

A. NO CHANGE