Instruction: Carefully assess the user's review for any strong expressions of sentiment, either positive or negative. Based on your analysis, select the most fitting sentiment option from the provided list as output.

Input:
I bought one a few months ago and it seems to be ideal for daily use.  I recently bought 3 more but found out that the new ones aren't double-walled like the other.  They feel lighter and more hollow sounding than my first one.  I'm not sure these are cheaper knock offs but I'll be exchanging them or sending them back for a refund.

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