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

Input:
I have one big problem with these ankle weights: they slip down and don't stay on well. I keep tightening them to no avail. so exercise is an exercise in frustration. Other than that, they seem to be well constructed and of good quality. I'm sure they will last a long time. But I don't recommend them, regardless.

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