Charlie is preparing a client's return. The client is single but claims his parents as his dependents to qualify him as head of household $(HOH)$ filing status. Charlie must do all the following to comply with IRS$-$required due diligence, except.

Select one:

a$.$ Charlie must provide documentation to the IRS to substantiate the amounts the taxpayer contributes to his parents' support along with proof of their residency.

b$.$ Complete Form $8867,$ Paid Preparer's Due Diligence Checklist, and submit it to the IRS with the taxpayer's tax return.

c$.$ Charlie must ask additional questions and document the taxpayer's answers to those questions and keep copies of any of the taxpayer's documents that were used to determine the eligibility for the HOH filing status.

d$.$ Charlie must not know or have reason to know that any information used in determining the eligibility of the HOH filing status is incorrect.