What does it mean when a documents or information is"privileged"?

A. The tax professional who prepared the document or information is the only person who may authorize its dislosure

B. the documents or information is not relevant to the determination of the taxpayer 's tax liability.

C. The IRS and other authorities may obtain and review the document or information ,but they may not use it against the client.

D. the document or information is protected from discovery and use by the IRS.