The correct answer is: a) Tiger
The tiger is an important symbol of Bihu celebrations in Assam. It is believed that the tiger is the guardian of the land and the people of Assam. The tiger is also a symbol of strength, power, and courage. During Bihu celebrations, people often wear tiger masks and dance in the streets. They also sing songs about the tiger and its importance to the culture of Assam.
The other options are incorrect because they are not as closely associated with Bihu celebrations as the tiger. The buffalo is a symbol of wealth and prosperity in Assam, but it is not as closely associated with Bihu celebrations as the tiger. The deer is a symbol of grace and beauty in Assam, but it is not as closely associated with Bihu celebrations as the tiger. The elephant is a symbol of strength and wisdom in Assam, but it is not as closely associated with Bihu celebrations as the tiger.