Which of the following is a festival of merriment and heralds the Assamese New Year and the onset of spring?

Bohag Bihu

The correct answer is Option (3) - Bohag Bihu

The festival of merriment that heralds the Assamese New Year and the onset of spring is called Bohag Bihu. Bohag Bihu, also known as Rongali Bihu, is one of the major festivals celebrated in the Indian state of Assam, marking the beginning of the Assamese New Year and the agricultural season. It is a joyous occasion characterized by traditional music, dance, feasting, and cultural performances.