Instruction: Determine the sentiment expressed by the user in her review from the provided choices, and respond by selecting one of the available options.

Input:
I had my left knee replaced in early January & used this product as prescribed by my physical therapist to strengthen my leg . I have used this product for over nine months with great results.
Thanks
 Vincent Avitello

Options:
A: very positive
B: positive
C: neutral
D: negative
E: very negative
Answer: B: positive