Vector Subtraction Rule Steps:

• Subtracting Y from X equals adding the negative of Y to X.
• Reverse Y to get -Y, which points opposite to Y with same magnitude.
• Attach tail of -Y to head of X.
• Z extends from tail of X to head of -Y.

Why A is correct:

• Diagram A matches the vector subtraction formula Z = X + (-Y), showing Z as the diagonal from X's tail to -Y's head in the parallelogram method.

Why the others are wrong:

• B shows X + Y, the sum instead of difference.
• C reverses X instead of Y.
• D scales vectors incorrectly, ignoring equal magnitudes.

Final answer: A