Who among from the following was the founder of Sikkim Praja Mandal?

Kazi Lhendup Dorji Khangsarpa

The correct answer is Option (3) → Kazi Lhendup Dorji Khangsarpa

Kazi Lhendup Dorji Khangsarpa: Leader of democracy movement in Sikkim; founder of Sikkim Praja Mandal and later leader of the Sikkim State Congress; in 1962 founded the Sikkim National Congress; after an electoral victory, he led the movement for integration of Sikkim with india; after the integration, Sikkim Congress merged with the indian National Congress.