Which of the following will result in an unfavorable direct materials efficiency variance? A) when the actual cost per unit of direct materials exceeds the standard cost of direct materials B) when the actual cost per unit of direct materials is less than the standard cost per unit of direct materials C) when the actual quantity of direct materials used per unit exceeds the standard quantity of direct materials allowed per unit D) when the actual quantity of direct materials used per unit is less than the standard quantity of direct materials allowed per unit