The correct answer is (a) Chandi Prasad Bhatt.
Chandi Prasad Bhatt was an Indian environmentalist and social activist who is considered to be the father of the Chipko movement. He was awarded the Gandhi Peace Prize in 1987 for his work in environmental protection.
Sunder Lal Bahuguna was another prominent environmentalist from Uttarakhand who was also involved in the Chipko movement. He was awarded the Padma Shri in 1982 and the Padma Vibhushan in 2009 for his work in environmental protection.
Jagat Singh Chaudhari “Jangli” was a social activist who worked for the rights of the tribal people of Uttarakhand. He was awarded the Padma Shri in 2001 for his work in social justice.
Kalyan Singh Rawat was a politician who served as the Chief Minister of Uttarakhand from 2002 to 2007. He was not an environmentalist.