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

Input:
Work, but color change is VERY difficult to see when submerged. Very subtle. Changes from Amber Red color to Dark Purple color. Tested with competing product, and timer is accurate.

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