Esther 2:12, Question 1. Why are the women discussed in the singular?

יב וּבְהַגִּיעַ תֹּר נַעֲרָ֨ה וְנַעֲרָ֜ה לָבוֹא ׀ אֶלהַמֶּלֶךְ אֲחַשְׁוֵרוֹשׁ מִקֵּץ הֱיוֹת לָהּ כְּדַת הַנָּשִׁים שְׁנֵים עָשָׂר חֹדֶשׁ כִּי כֵּן יִמְלְאוּ יְמֵי מְרוּקֵיהֶן שִׁשָּׁה חֳדָשִׁים בְּשֶׁמֶן הַמֹּר וְשִׁשָּׁה חֳדָשִׁים בַּבְּשָׂמִים וּבְתַמְרוּקֵי הַנָּשִׁים

12. And when the turn came for each young woman to come to the king Achashverosh at the end of her being like the law of women twelve months because so were filled the days of their anointing: six months in myrrh oil and six months in spices and cosmetics of women.

In literature, an author often chooses to write about singular characters to make an stronger emotional impact on a reader. For instance, in the classic novel, The Grapes of Wrath, John Steinbeck writes about the American Dust Bowl of the early 1930’s, but focuses in on a particular fictional family, the Joad’s to humanize the issues discussed in the other chapters of the book. Perhaps, the verse wants us as readers to put our feet into the shoes of the poor girls (here and in the next verse) put into this position.