The correct answer is (D) A short composition or discourse, particularly on a religious or political subject; a form of anthem; a brief pamphlet or treatise, or leaflet for general distribution.

Tract comes from Middle English tracte, Latin tractatus (treatise).

Examples of use:

• His much vaunted novel proved too be as dull as the dullest religious tract.
• Her experience in the field was covered in the notes at the end of my tract.