Como
Explanation:
"Como" in that sentence is asking, "How is the new girl?" "Ella is muy simpatica" is used to describe the girl as nice in response to the question.
"Quien" would be asking, "Who is the new girl?" "Ella is muy simpatica" doesn't relate to that question.
The answer is “Hemos olvidado”
Conocemos
Sabe
Conocen
Saben
Sabe
Conozco
Sabe
Sabe
Conocer
Saben
