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 have used this mat for a year and a half several times a week and it is STILL too slippery to use without a rug or towel over it. I tried scrubbing it with coarse kosher salt like they suggested, even doing that twice and no change in slipperiness. It is very heavy but i don't care because I only walk from the car to the studio; would hate to have to lug it on public transport. Seems very sturdy and will probably last for many years. Unfortunately, I regret buying it and will be looking for a different brand.

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