The correct answer is: A. 6th April, 1930
The Salt Satyagraha was a major nonviolent protest campaign in India led by Mahatma Gandhi. It was launched on 6 April 1930, when Gandhi and his followers marched to the coastal town of Dandi to make salt from seawater in defiance of the British salt monopoly. The campaign lasted for more than a year and involved millions of Indians. It was a major turning point in the Indian independence movement and led to the British granting India independence in 1947.
The Salt Satyagraha was observed in Bihar on 6 April 1930. On that day, Gandhi and his followers marched to the coastal town of Dandi to make salt from seawater in defiance of the British salt monopoly. The march was a major turning point in the Indian independence movement and led to the British granting India independence in 1947.
The other options are incorrect because they are not the dates on which the Salt Satyagraha was observed in Bihar.