Option 1: The administration of Daman and Diu and Puducherry has been merged together. This option is incorrect.

Option 2: The administration of Puducherry and Dadra and Nagar Haveli has been merged together. This option is incorrect.

Option 3: The administration of Puducherry and Andaman and Nicobar Islands has been merged together. This option is incorrect.

Option 4: The administration of Dadra and Nagar Haveli and Daman and Diu has been merged together. This is the correct answer.

In January 2020, the Indian government announced the merger of Dadra and Nagar Haveli and Daman and Diu, forming a single union territory. Dadra and Nagar Haveli was a union territory located near Gujarat, while Daman and Diu was another union territory located near Maharashtra. The merger was aimed at improving administrative efficiency and coordination between the two territories. This move resulted in the formation of a larger union territory with a combined population and resources.