Mary, a vsc-certified greeter, reviews the taxpayer's completed form 13614-c, page 2, to identify what potential volunteer certification level is needed for this tax return. mary sees the taxpayer has checked the "yes" box indicating he has self-employment income and the certification level next to the question is (a). all other questions answered "yes" have a (b) certification. when mary assigns the return to a tax preparer, what tax law certification level should the tax preparer have?