The first suggestion for "calze" is "(you) are apt." What does that even mean? Also, it lists singular versions of both sock and stocking, whereas calze is plural.
The lists often contain words in the singular, where the sentence uses a plural form. Beware!
The Zanichelli Italian Dictionary lists two separate italian words for sock/socks: the feminine la calza, le calze, and the masculine il calzino, i calzini.
Why stockings? Where is the right answer socks? Only singular form sock...
duolingo can be fickle like that. 'They are my socks' sounds correct. That's what I did, and it told me I was correct.
SO if "calze" is plural how come "le mie" is correct, shouldn't it be "i miei"?
Strange that socks and stockings are the same word, because they're really not the same item. I'm going to suggest "tights" as an alternative answer, which is the word I used for stockings and got wrong. But maybe there is a different word for tights, as they are also a little different to stockings, being joined at the top. ?