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

Input:
As a referee in the swim meets, a good loud and clear whistle is a must. My son always told me that he would know right a way if I was a ref blowing the whistle. Everyone in the upper deck could hear it. I now have to put the earplugs in my ears to filter out the sound because this whistle sound can really pierce through your ears... I am ordering another one as a spare!

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