I think it was the humanitarians but also the slaves spoke up about their mistreatment and encourage people that slavery is wrong. If the slaves didn't tell people about their misery nobody would know or help. I think it was slaves and humanitarians that abolish slavery. I hope this helps.
Answer from: Quest
do u have choices? ? or no?
Answer from: Quest
monarchy doesn’t have to have the hereditary element. there have been elective monarchies in the past where you choose your king-for-life and when he dies elect someone else for the job.