Assertion: The people of Bangladesh started a struggle to liberate Bangladesh from Pakistan in 1971.

Reason: The Pakistani rulers were unwilling to accept the Awami League's demand for federation and rather arrested Sheikh Mujib and unleashed a reign of terror on the people of East Pakistan.

Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.

Beginning in 1970, Pakistan faced its biggest internal crisis. The country's first general election produced a split verdict- Zulfikar Ali Bhutto’s party emerged a winner in West Pakistan, while the Awami League led by Sheikh Mujib-ur Rahman swept through East Pakistan The Pakistani rulers were not willing to accept the democratic verdict. Nor were they ready to accept the Awami League’s demand for a federation. the Pakistani army arrested Sheikh Mujib and unleashed a reign of terror on the people of East Pakistan. In response to this, the people started a struggle to liberate ‘Bangladesh’ from Pakistan.