The lesson states: A) If it/he/she is is followed by un/une/le/la... (any form of article / determinant) - it is a beautiful dress / she is a nice person - then you will use c'est.
Now not being a native french speaker, and still very much a student, it still feels wrong to use “c’est” here, as so the lesson also states: B) il est/elle est for statements and opinions related to specific things
As we’re talking about a specific, pre-mentioned person, “Valentine,” the obvious answer is “Elle est une très bonne danseuse.” However, the “C’est une très bonne danseuse” is listed as correct.Is this an error? Or what am I getting wrong here?"