Question

any four reasons for which east pakistan had to start liberation movement

Answer 1

they were a minority
they were given very less seats in the Congress party
they felt that they would be overthrown by the Indians due to their small numbers in comparison to indians( Hindus)
they felt that they needed seperate rights for themselves
this also started because of the change in court language from Urdu to hindi

Answer 2

Since partition Pakistan has had 2 stances on foreign aid and development funds allocation. First it was according to size, since current Pakistan and baluchistan was larger is size and current Bangladesh larger in population, funds were given to larger size (by land size). Development happened in Pakistan but not in Bangladesh while resources were being stripped from Bangladesh to make current Pakistan prosper. Bangladeshis were against it and then during election, Bangladeshis won majority of seats but were not allowed to make government, followed by banning of Bangla language. This was the last straw.

At the same time, India was in a position similar to Pakistan (with respect to Afghan refugees), India was bearing weight of these refugees and finally Indira Gandhi (as much as I hate her policies) decided on a good policy, rather than Indian economy (which was already under prwssure) bearing the weight of these refugees, we armed them and sent them back to fight.