Dr. Muller is a developmental psychologist who studies adopted children, comparing them to those who are reared by their biological parents. Which of psychology's big questions is she MOST interested in answering?

"nature or nurture?"

Explanation:

Based on the information provided within the question it can be said that the psychological question that she is most interested in answering is "nature or nurture?". This question asks whether the behaviors and characteristics of a child come from a biological instinct/genetics (nature) or are learned from the those around them (nurture).