"She is my daughter."
Translation:C'est ma fille.
This is a rule you will have to apply VERY often on Duolingo. In French, "c'est" (sing.) and "ce sont" (plural) are used in a large variety of expressions, when a pronoun (it, she, he, they) is subject of verb "être" and followed by a nominal group, ie: article (+ adjective) + noun. - it is + noun => c'est - she is + noun => c'est - he is + noun => c'est - they are + noun => ce sont
Sitesurf with all due respect your explanation is a bit wrong and misleading to those trying to learn the language. I was turned on to this app bc a friend of mine notified me of this app et je suis francais. :). The "elle. .." form is too acceptable, though the answer given by duolingo is in fact the most grammatically correct. However depending on the purpose of Iearning Francaise, the answer given can or cannot be helpful. if you are learning to write in class this answer is perfect. If you are learning to speak, this will make you sound a bit strange to the common speaker. Still however this is a cute app. :)
elle est ma fille... she is my daughter... c'est ma fille ... it's my daughter.... but i think it will depend on the spoken context...which one would be more appropriate... I am just beginning to learn... so I am not sure whether I am correct...but I do think elle est ma fille is not incorrect...like the computer of Duo states....