**Answer:**

The correct answer is option 'A' - October 31st, 2019.

**Explanation:**

On October 31st, 2019, the state of Jammu and Kashmir was officially bifurcated into two separate Union Territories - Jammu and Kashmir, and Ladakh. This significant move was announced by the government of India on August 5th, 2019, when Article 370 of the Indian Constitution, which granted special status to Jammu and Kashmir, was abrogated.

Here is a detailed explanation of the events leading up to the bifurcation:

**1. Abrogation of Article 370:**

- On August 5th, 2019, the government of India made a historic decision to abrogate Article 370 of the Indian Constitution, which granted special status to Jammu and Kashmir.
- This move revoked the autonomous status of Jammu and Kashmir and brought it under the direct control of the central government.

**2. Reorganization of the state:**

- Along with the abrogation of Article 370, the government also announced the reorganization of the state of Jammu and Kashmir.
- The state was to be bifurcated into two separate Union Territories - Jammu and Kashmir, and Ladakh.

**3. Implementation of bifurcation:**

- The implementation of the bifurcation took place on October 31st, 2019.
- On this day, the two Union Territories of Jammu and Kashmir, and Ladakh came into existence.
- The Union Territory of Jammu and Kashmir consists of the regions of Jammu, Kashmir, and Ladakh, while the Union Territory of Ladakh comprises the districts of Leh and Kargil.

**4. Administrative changes:**

- With the bifurcation, the governance structure in the region also underwent changes.
- The Union Territory of Jammu and Kashmir is now administered by a Lieutenant Governor appointed by the President of India.
- The Union Territory of Ladakh is also administered by a Lieutenant Governor.

Overall, the bifurcation of Jammu and Kashmir into two Union Territories marked a significant shift in the political and administrative landscape of the region. This move aimed to bring about better governance, development, and integration of Jammu and Kashmir and Ladakh with the rest of India.