The Best Cost Driver That Johnson Has for Variable Factory

The best cost driver that Johnson has for variable factory overhead in the assembly department is machine hours. During July, the company budgeted 360 machine hours and $3,240 for its Oklahoma plant's assembly department. The actual variable overhead incurred was $3,435, which was related to 375 machine hours.
The variable overhead spending variance and variable overhead efficiency variance are:

A) Variable overhead spending variance $60 U, Variable overhead efficiency variance $135 U
B) Variable overhead spending variance $30 U, Variable overhead efficiency variance $135 U
C) Variable overhead spending variance $135 U, Variable overhead efficiency variance $30 U
D) Variable overhead spending variance $60 F, Variable overhead efficiency variance $135 U