The correct answer is:
Yes, Leslie’s opponent was allowed to change positions to receive the serve.
From The Code, Item 35:
Item 35 makes it clear that the returner can move while the server is serving, even if the movement is distracting. However, a movement or sound made solely to distract an opponent is not allowed.
In Leslie’s case, since her opponent was moving to get in a better position to return the serve, the movement was allowed. Furthermore, if Leslie had served her second serve rather than stopping her motion, and if her serve had gone out, it would have counted as a double fault.
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