Final answer:
Betty's infant daughter likely has a difficult temperament, characterized by frequent crying, routine negative moods, and difficulty adapting to change.
Step-by-step explanation:
According to research conducted by Thomas and Chess, Betty's infant daughter, who cries often and is routinely in negative moods and reacts to change with difficulty and slowness, most likely has a difficult temperament. This classification is part of the three temperaments they identified: easy, difficult, or slow to warm up. A difficult temperament is characterized by negative emotions and a hard time adapting to change and regulating emotions.