By which month monsoon winds retreat from Bihar?

The correct answer is: B. October

The monsoon winds retreat from Bihar in October. The monsoon season in India lasts from June to September. The monsoon winds blow from the southwest to the northeast, bringing heavy rains to the country. The monsoon winds retreat in October, as the sun moves south.

Option A: September is too early. The monsoon winds are still blowing in September.

Option C: November is too late. The monsoon winds have already retreated by November.

Option D: December is incorrect. The monsoon winds do not blow in December.