Which of the following statements is [ are} true? 0 a. an unfavourable direct materials variance always results in an unfavourable direct labour efficiency variance b. none of these 0 c. an unfavourable DM quantity variance and an unfavourable DM price variance are always accompanied by an unfavourable DM flexible budget variance 0 d. an unfavourable direct labor rate variance always results in a favourable labor efficiency variance. Clear my choice