Which of the following is subject to tax return preparer penalties?

a$.$ Meredith is the director of Federal taxes for a C corporation.

b$.$ Sammy is a volunteer who prepares returns at the retirement home under the IRS Tax Counseling for the Elderly program.

c$.$ Abbie prepares her mother$$s tax returns for $$50$ a year. A CPA, Abbie would charge a client $$750$ for completing a similar return.

d$.$ Lizzie, the firm$$s administrative assistant, makes copies of returns and assembles the mailings that the client must make to the agencies.