In producing product $A A, 6,300$ pounds of direct materials were used at a cost of $\$ 1.10$ per pound. The standard was 6,000 pounds at $\$ 1.00$ per pound. The direct materials quantity variance is:
a. $\$ 330$ unfavorable.
c. $\$ 600$ unfavorable.
b. $\$ 300$ unfavorable.
d. $\$ 630$ unfavorable.