The correct answer is (D) A letter (especially an official one); a written message sent (or to be sent) from an official source; a formal letter from someone in authority.

Missive comes from Middle English missive (letter), French missive, Latin missivus (a letter), mittere (to send).

Examples of use:

• A missive from the court summoned him to appear for jury duty.
• He received news of his award by a missive from the Board of Governors.