Final answer:
The Methodist Church (option 1) is the mainstream Protestant denomination that spoke out against slavery, along with the Baptist and Presbyterian denominations having some involvement with African slaves in southern colonies.
Step-by-step explanation:
The mainstream Protestant denomination that spoke out against slavery was the Methodist Church (option 1)
The Methodist and Baptist churches attracted enslaved individuals due to their styles of worship, which emphasized emotional responses to scripture. They also allowed enslaved individuals to freely express messages of hope, struggle, and overcoming adversity through spiritual songs.
The Presbyterian denomination also reached out to African slaves in southern colonies by establishing churches that received African slaves into the congregation.