Which of the Following Defines a Legal Letter

Which of the following defines a legal letter?

A) An audit inquiry sent to a client's external and in-house legal counsel to obtain information about litigation, assessments, and claims.
B) A letter comprising the auditor's report that is required by generally accepted auditing standards or is included at the auditor's discretion.
C) A statement in which a CPA orders inquiry and analytical procedures to provide limited assurance that no material modifications should be made to the financial statements.
D) An engagement in which a CPA applies accounting and financial expertise to assist management in the presentation of financial statements.