Instruction: Given the user's review, identify the user's sentiment from the listed options. Answer using one of the options.

Input:
This device really works! At first I was doubtful but then realized I had a red warning light displayed instead of 2 Blue LED lights. Once the blue LED lights were displayed, the bugs were gone.

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