Direct labor

Which of the following might explain an adverse direct labour cost variance? 1. Working overtime 2. Idle time 3. Poor productivity A. Reasons 1 and 2 only B. Reasons 1 and 3 only C. Reasons 2 and 3 only D. Reason 3 only Answer is D. I am clear about it. My question is if it ask for adverse direct labor efficiency variance so what will be answer? Like here, we are not including A and B as it is asking for direct labor cost and these are both indirect labor cost.