The correct answer is option 2: Bipin Chandra Pal was a member of the extremist group of Congress.

The extremist group, also known as the Lal, Bal, Pal group, consisted of three prominent leaders – Lala Lajpat Rai, Bal Gangadhar Tilak, and Bipin Chandra Pal. They advocated for more radical methods to achieve independence from British rule and were known for their fiery speeches and nationalist ideologies.

Option 1 is incorrect because Bipin Chandra Pal was not a member of the moderate group of Congress. The moderate group, led by leaders like Gopal Krishna Gokhale, believed in more gradual and constitutional methods to bring about political reforms and independence.

Option 3 is incorrect as well. Bipin Chandra Pal did not hold the position of the Minister of Defence in the first Government of independent India. This position was held by Sardar Vallabhbhai Patel.

Option 4 is also incorrect. Bipin Chandra Pal was not the Chief Minister of West Bengal. He was a prominent freedom fighter and nationalist leader, but he did not hold any administrative positions in the government.

In conclusion, option 2 is the correct answer as Bipin Chandra Pal was a member of the extremist group of Congress