"Is this your girl?"
Translation:זאת הילדה שלכם?
The use of the word "האם" is more formal, and isn't used much in the spoken day-to-day language. It's more relevant to written communication.
I'm a beginner, but the Tips and Notes have something about this. Best I understand, the possessive structure = definite article + noun + possessive adjective. Like here: literally, "the-girl yours"--article first, then noun, then possessive adjective.
It's now saying the answer is זו! מה? We never learnt this word and it's not in the choices. Ggggrrr