Cox Engineering Performs Cement Core Tests in Its Laboratory During March, the Laboratory Performed 2,000 Core Tests

Cox Engineering performs cement core tests in its laboratory. The following standards have been set for each core test performed: $\begin{array}{lcc}&\text { standard Hours or Quantity} &\text {standard price or Rate }\\\text { Direct materials } & 3.0 \text { pounds } & £ 0.75 \text { per pound } \\\text { Direct labour } & 0.4 \text { hours } & £ 12.00 \text { per hour } \\\text { Variable manufacturing overhead } &0.4 \text { hours } & £ 9.00 \text { per hour }\end{array}$

During March, the laboratory performed 2,000 core tests. On March 1 no direct materials (sand) were on hand. Variable manufacturing overhead is assigned to core tests on the basis of direct labour hours. The following events occurred during March:
8,600 pounds of sand were purchased at a cost of £7,310.
7,200 pounds of sand were used for core tests.
840 actual direct labour hours were worked at a cost of £8,610.
Actual variable manufacturing overhead incurred was £3,200.
-The variable overhead efficiency variance for March is

A) £320 unfavourable.
B) £320 favourable.
C) £360 unfavourable.
D) £360 favourable.