A 16-year-old assigned-female-at-birth adolescent presents to a psychiatric clinic accompanied by their parent. The adolescent reports a persistent and distressing incongruence between their experienced gender and assigned sex that has been present since age 11. They describe a strong desire to be treated as male, significant discomfort with their physical sex characteristics since the onset of puberty, and a consistent identification as male in online communities for the past 3 years. They report depressed mood, social withdrawal, and avoidance of activities requiring gender-specific clothing such as swimming. PHQ-A score is 14 and GAD-7 is 11. Their parent is supportive and confirms the consistency and persistence of these experiences. The adolescent has no history of psychotic symptoms, trauma, or substance use. The PMHNP is conducting a comprehensive assessment. Which of the following BEST reflects appropriate diagnostic reasoning?