Explanation:

- Option 1: Kheda Satyagraha

- Took place in 1918.

- Led by Mahatma Gandhi.

- A non-violent protest against British tax policies.

- Option 2: Partition of Bengal

- Occurred in 1905.

- Implemented by the British as a divide-and-rule policy.

- Created a separate Muslim-majority province, affecting unity.

- Option 3: Arrival of Simon Commission

- Arrived in India in 1928.

- Aimed to review the Government of India Act 1919.

- Faced nationwide protests for having no Indian members.

- Option 4: Dandi March

- Started in 1930.

- A salt satyagraha led by Gandhi.

- Protested the British monopoly on salt production.

Given all these events, your answer of Option 2: Partition of Bengal being the earliest is correct.