Final answer:
The subject of the question is Arts, and the student's favorite musical is 'Phantom of the Opera.'
Step-by-step explanation:
The subject of your question is Arts. You are referring to a poster which represents the musical 'Phantom of the Opera' and is colored red, black, and gold. Based on your statement, 'It is my favorite musical,' it is safe to assume that the 'Phantom of the Opera' is your favorite musical.