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:
We took this filter on a 12-day trek through the mountains and desert of New Mexico.  Fining drinkable water was a huge issue.  However, we were able to purify even the worst of water with this filter with no worries of picking up any sort of nasty viruses or bacteria.  Our water came from streams that had cattle, buffalo, elk and other wildlife all around, but the First Need XL had it appearing and tasting as pure as bottled water.

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