Sentence Correction (SC) | Re: The organic food industry has organized a successful grassro

The organic food industry has organized a successful grassrootscampaign—using Web sites, public meetings, and also mass mailings—that have convinced the Department of Agriculture to change the proposed federal regulations for organically grown food.

A. using Web sites, public meetings, and also mass mailings—that have convinced -- subject-verb agreement -- campaign have
B. using Web sites, public meetings, and mass mailings—that has convinced - Correct
C. by using Web sites, public meetings,