Subject: Disagreement with professor's response
Dear Professor, 

I wanted to express my disagreement with your last answer to my question.
Compose an email to your professor expressing disagreement with their answer and articulate why you think your opinion is valid.
Dear Professor, 

I wanted to express my disagreement with your last answer to my question. I believe that the answer you provided is incomplete and does not fully consider my question. I believe my understanding of the given material is correct and that my opinion is valid. I would appreciate if you could take the time to explain your response and provide further clarification. 

Thank you for your time and consideration.

Sincerely,
[Your Name]