Answer:
The correct answer is: "atrevida".
Explanation:
You are talking about a girl (Gloria), you are saying "Gloria es una chica ....." so the correct word would be "atrevida". It cannot be "atrevidas", because it is a plural word, and Gloria is only one girl. "atrevido" is a singular word, but referred to the masculine gender. And "atrevidos" is a plural word, and referred to the masculine gender as well.
