Which of the following is observed on the fourth day of Diwali celebrations?

A Govardhan Puja
B Dhanteras
C Bhai Dooj

Govardhan Puja, also known as Annakut or Annakoot, is a Hindu festival celebrated in India, primarily in the northern states. It holds great religious and cultural significance, especially among devotees of Lord Krishna.

The correct answer is Govardhan Puja.