The colonial policies and practices that played a part in peaceful or violent transitions to self-rule were very complex. One major one which had a very important role here was Apartheid. This was an important policy which had at its core racial segregation between black and white people.
Possibly the last one or the third one.
I believe it is workers had more negotiating power when standing together as a group rather than they had individually," since it would be very detrimental to a company if their entire workforce quit at once.