The Limbu people of Sikkim have their own language, which belongs to the:

Indo-Aryan language family
Dravidian language family
Tibeto-Burman language family
Austroasiatic language family

The correct answer is: c) Tibeto-Burman language family.

The Limbu people are an ethnic group native to the eastern Himalayas. They are the largest ethnic group in Sikkim, India, and they also live in Nepal, Bhutan, and China. The Limbu language is a member of the Tibeto-Burman language family, which is the largest language family in Asia. The Tibeto-Burman language family includes over 400 languages spoken by over 400 million people. The Limbu language is spoken by over 500,000 people.

The Indo-Aryan language family is the second largest language family in Asia. It includes over 400 languages spoken by over 2 billion people. The Indo-Aryan language family includes Hindi, Urdu, Bengali, Punjabi, Marathi, Gujarati, and Nepali.

The Dravidian language family is the third largest language family in Asia. It includes over 200 languages spoken by over 200 million people. The Dravidian language family includes Tamil, Telugu, Kannada, Malayalam, and Tulu.

The Austroasiatic language family is the fourth largest language family in Asia. It includes over 100 languages spoken by over 100 million people. The Austroasiatic language family includes Vietnamese, Khmer, and Mon.