Step 1: Identify the instrument.
TAT (Murray & Morgan) is a projective test in which examinees create stories about pictures to reveal implicit motives and conflicts.
Step 2: State the standard composition.
The complete set contains 30 picture cards + 1 blank card (used to elicit a story without a visual cue) $= 31$ total. Examiners choose age/sex-appropriate subsets, but the canonical full set is thirty-one.
Step 3: Conclude.
\[
\boxed{\text{31 cards in total (Option D).}}
\]