Bihar (together with Orissa) was separated from the Bengal Presidency to form a new province in:

Bihar, together with Orissa, was separated from the Bengal Presidency to form the new province of Bihar and Orissa on 1 April 1912.

Background:

• Bihar and Orissa had been part of the Bengal Presidency since the time of the English East India Company.
• During the partition of Bengal (1905), Bihar and Orissa remained in the western province of Bengal.
• When the partition was annulled, Bengal was reunited, but Bihar and Orissa were separated to form a new province.

The new province:

• The province of Bihar and Orissa was created on 1 April 1912, with its capital at Patna.
• It had a Lieutenant-Governor at first; later it became a Governor's province.

Bihar Day:

22 March is celebrated as "Bihar Diwas" (Bihar Day), marking the announcement of the formation of the province in 1912.

The movement for a separate Bihar:

Leaders such as Sachchidananda Sinha, Mahesh Narayan and Mazharul Haq had campaigned for a separate province of Bihar, as the people of Bihar felt that they were neglected and that the Bengalis dominated the jobs and administration.

Sachchidananda Sinha is regarded as the "father of modern Bihar".

Later changes:

• On 1 April 1936, Orissa was separated from Bihar and became a separate province; 1 April is celebrated as "Utkal Divas" (Odisha Day).
• In 2000, the state of Jharkhand was carved out of the southern part of Bihar (15 November 2000).

Other provinces created by reorganisation:

• Assam became a separate province again in 1912 (Chief Commissioner's province).
• Sind was separated from the Bombay Presidency in 1936.

About Bihar:

It was the centre of ancient empires such as Magadha, the Mauryas and the Guptas, with the capital at Pataliputra (Patna).

Why not the other options?

• ✗1905 was the year of the partition of Bengal.
• ✗1936 was the year Orissa became a separate province.
• ✗1947 was the year of Independence.