Assume (1) the quantity of materials purchased equals the quantity used in production, (2) the materials price variance is $400 unfavorable, and (3) the materials quantity variance is $200 favorable. Given these assumptions, which of the following statements is true?

a. The materials spending variance must be $600 favorable.

b. The materials spending variance must be $600 unfavorable.

c. The materials spending variance must be $200 favorable.

d. The materials spending variance must be $200 unfavorable.