The correct answer is B. 83 seats.
The final phase of elections in February, 2005 in Bihar was for 83 seats. The elections were held in three phases, with the first phase being held on February 5, 2005, the second phase on February 12, 2005, and the final phase on February 19, 2005. The elections were held to elect members to the 243-member Bihar Legislative Assembly. The Janata Dal (United) won the elections with 145 seats, followed by the Rashtriya Janata Dal with 75 seats and the Bharatiya Janata Party with 55 seats. The remaining 30 seats were won by independent candidates and other parties.
Option A is incorrect because it is the number of seats that were contested in the first phase of the elections. Option C is incorrect because it is the number of seats that were contested in the second phase of the elections. Option D is incorrect because it is not a valid option.