$5.$ Which of the following statements is false regarding tax return preparers?

a$.$ Only a person who signs a return as the preparer may be considered the preparer of the return.

b$.$ Unpaid preparers, such as volunteers who assist low$-$income individuals, are not considered to be preparers for purposes of preparer penalties.

c$.$ An employee who prepares the return of his or her employer does not meet the definition of a tax preparer.

d$.$ The preparation of a substantial portion of a return for compensation is treated as the preparation of that return.