Bohag Bihu marks the beginning of the:

Assamese New Year
Harvest season
Monsoon season
Winter season

The correct answer is: a) Assamese New Year.

Bohag Bihu is the most important of the three Bihu festivals celebrated in Assam, India. It marks the beginning of the Assamese New Year and the harvest season. The festival is celebrated with great pomp and show, with people dancing, singing, and feasting.

The other options are incorrect because:

  • Harvest season: Bohag Bihu marks the beginning of the harvest season.
  • Monsoon season: Bohag Bihu is celebrated before the monsoon season.
  • Winter season: Bohag Bihu is celebrated in the spring.