Answer: The correct answer is "d. actual hours exceeded standard hours allowed for the actual output.".
Explanation: The variation in work efficiency is equal to the real hours minus the standard hours plus the standard rate.
(AH - SH) × SR = Variation in work efficiency.
Therefore, if the actual hours are greater than the standard hours, an unfavorable variation occurs.
AH > SH = unfavorable variation.
AH < SH = favorable variation.