What is a grassroots effort by abolitionists to pressure the government to outlaw slavery? protesting the mexican-american war as an attempt to spread slavery boycotting businesses that used slave labor enacting legislation to end the importation of slaves promoting federal legislation to end the spread of slavery into the territories?

A grassroots effort would be boycotting businesses that used slave labor. Boycotting a business means that you no longer purchase items from that business. The abolitionists no longer purchased products from businesses that used slave labor, thus decreasing the sales of those businesses, and hitting them economically. This is an effective means of making change if enough people are on board.