'Utkal Diwas', which was celebrated on 1st April 2025, marks the anniversary of the statehood of __________.

The correct option is Odisha.

Step-by-step Explanation:

1. Historical Context of Utkal Diwas:
Utkal Diwas, also known as Odisha Day, is celebrated every year on the 1st of April to commemorate the formation of the state of Odisha as a separate province.

2. Creation of the State:
On April 1, 1936, the state of Odisha (formerly known as Orissa) was carved out as a separate linguistic province during the British rule in India. It was separated from the combined Bihar and Orissa Province due to the persistent efforts of prominent leaders and the local population demanding recognition of their distinct linguistic identity.

3. Significance:
Therefore, the celebration of 'Utkal Diwas' on 1st April 2025 marked the anniversary of the statehood of Odisha.