What do you prefer? A. We thank the reviewer for their helpful comments B. We thank the reviewer for her helpful comments [RK] If this is, as it appears to be, a reference to a specific reviewer, then use their preferred pronoun, or possibly a conventional singular one if you know their name and they haven't specified a preference. [RK] Only if they aren't known, and especially if they are one from a pool, then "their". [RK] Or make them plural - We thank the reviewers for their helpful comments. [RK] Or rephrase to sidestep the issue (though it isn't clear to me here what that option would be) Regards, Richard.
