The correct answer is (b). The Sikkim National Party (SNP) was a political party in Sikkim, India. It was founded in 1947 by Tashi Namgyal, the Chogyal of Sikkim. The SNP represented the interests of the Bhutia-Lepcha communities of Sikkim. The party was opposed to the merger of Sikkim with India. It was also opposed to the influx of Nepali immigrants into Sikkim. The SNP was dissolved in 1975 after Sikkim became an Indian state.
Option (a) is incorrect because the SNP did not represent the interests of ethnic Nepalis. The SNP was a Bhutia-Lepcha party.
Option (c) is incorrect because the SNP did not represent the interests of landowners and zamindars. The SNP was a party of the Bhutia-Lepcha people.
Option (d) is incorrect because the SNP did not represent the interests of socialist and communist groups. The SNP was a party of the Bhutia-Lepcha people.