What if you looked up in a dictionary?
This is what I found for "pretty": (re. women) jolie, gentille, mignonne, fine; (other) beau, attrayant, magnifique, superbe.
For your information, the drop menu is not a dictionary and it is not dedicated to the very sentence you are translating. It is just a glossary of a few possible translations, without consideration of possible context. But I am sure you had already understood that subtle difference.
possessives adjectives agree with the object, not with the owner.
ma enfant does not work for technical reasons: there is a sound conflict with A-EN.
that is why, even if the "enfant" is a girl (enfant can be either masculine or feminine: un enfant or une enfant), possessive "ma" has to be changed to "mon" as if the "enfant " were a boy.
We have been lenient in most sentences, because the course does not teach the informal translations for "kid" = un gamin/une gamine, un/une môme, un/une gosse.
But frankly, I wish we had never accepted "kid" if we could not properly match the French register of speech.
We should probably add the French informal words to the next version of the tree.