Instruction: Carefully assess the user's review for any strong expressions of sentiment, either positive or negative. Based on your analysis, select the most fitting sentiment option from the provided list as output.

Input:
I have been using Trackman for 1.5 months. It is time to write review. I like it very much. It takes about 1 day for me to get used to trackball.
Features that I like most:
1. no hand and wrist movement - thumb only (you need to learn how to use thumb to move cursor/mouse precisely)
2. comfortable shape (45 degree wedge) - no wrist twist
3. carpal tunnel syndrome is not haunting me!

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