Explanation:

- Chyap-Brung: This is indeed the traditional musical instrument of the Limboo community of Sikkim. It is a type of drum used in various cultural and religious ceremonies. It holds significance in their traditional music.

- Chutkay: This is not a recognized traditional instrument associated specifically with the Limboo community. It might be a term, but not widely known in this context.

- Naumati: This generally refers to a set of traditional instruments used in Nepal and parts of India. It includes a group of musicians and is not specific to the Limboo community.

- Jeurum Silly: This term aligns more with Limboo cultural practices, specifically a dance form or event, rather than a musical instrument.

Correct Answer: Chyap-Brung