Please answer this question

[Mhsn]

Could you explain this questions answer?

İf a partical of sand,................., manages to become lodged under a contact lens, severe irritation can result.
A) no matter small, B) however small, C)small, D) but small

[Torsten]

First you should tell us what you think is the correct answer.

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[Mhsn]

Actually I am not sure but I thought that "small" C may be true.But the answer is B however small. I could't get it.

[Torsten]

The correct answer is 'however small'. It means, 'no matter how small the particle might be'. Please note the correct spelling of the word 'particle'.

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[Mhsn]

I really appreciate for your explanation and correction.