Which statement best describes a Kovel engagement?

a$.$ Kovel engagements set forth minimum standards of conduct that practitioners must meet when practicing before the IRS.

b$.$ Kovel engagements apply to services related to non$-$criminal IRS tax matters.

c$.$ Kovel engagements require a material advisor to disclose or $$register$$ any reportable transactions.

d$.$ Kovel engagements apply where a client legal counsel has hired KVI to perform tax services related to legal advice being provided by the attoneys.