Generally speaking it was the "Quakers" who pushed for the abolition of slavery, although there were people in practically every faith who pushed for this as well.
Quakers were the Christian religious group who pushed for the abolition of slavery. Option A is correct.
Quakers, also known as Friends, are a historically Christian group of religious movements formally called the Religious Society of Friends.
This Religious Society of Friends played a fundamental role in the abolition movement against slavery in both the United Kingdom and in the United States of America. They were among the first white people to denounce slavery in the American colonies and Europe.
