The correct answer is C. 1934.
The Bihar Congress Socialist Party was formed in 1934 by a group of young Congressmen who were inspired by the ideology of socialism. The party’s main objective was to achieve social and economic justice for the people of Bihar. The party played a significant role in the freedom struggle and in the development of Bihar after independence.
The other options are incorrect. Option A is incorrect because the Bihar Congress Socialist Party was not formed in 1930. Option B is incorrect because the Bihar Congress Socialist Party was not formed in 1931. Option D is incorrect because the Bihar Congress Socialist Party was not formed in 1939.