Explanation:

- Option 1: Nalgonda incident

- This incident is correct and marked the beginning of the Bhoodan Movement.

- In 1951, Vinoba Bhave visited Pochampally in Nalgonda district, where he was moved by the plight of landless villagers. This inspired him to start the Bhoodan Movement.

- Option 2: Srikakulam incident

- Not related to the initiation of the Bhoodan Movement.

- The Srikakulam peasant movement took place later and is connected to different leftist movements in India.

- Option 3: Naxalbari incident

- This incident is unrelated to Bhoodan and occurred much later, in 1967.

- It led to the rise of Naxalite-Maoist insurgency but not the Bhoodan Movement.

- Option 4: Madhubani incident

- This incident is not associated with the Bhoodan Movement either.

- Madhubani is more known for its art than any land-related reform movements.