What affect did colonialism in Rwanda have on the relationships between Hutu and Tutsis?

The Belgian rulership in Rwanda brought Hutu and Tutsis together while they were there.

The Belgian rulership favored Tutsis, causing Hutus to develop animosity towards them.

There was never a real colonial effort in Rwanda, so the tribes were self-ruling.

The Belgian rulership favored Hutus, causing the Tutsis to riot in protest.