Madengrad Company manufactures a single electronic product called Precisionmix. This unit is a batch-density monitoring device attached to large industrial mixing machines used in flour, rubber, petroleum, and chemical manufacturing. Precisionmix sells for $900 per unit. The following variable costs are incurred to produce each Precisionmix device:

Direct labor                          $180

Direct materials                       240

Factory overhead                     105

Total variable production costs        525

Marketing costs                        75

Total variable costs                   $600

Madengrad's income tax rate is 40%, and annual fixed costs are $6,600,000. Except for an operating loss incurred in the year of incorporation, the firm has been profitable over the last 5 years.

Assume a 10% increase in annual fixed costs, a 20% unit cost increase for direct labor, and a reduction in unit material costs of 25%, with no change in selling price. After incorporating these changes, Madengrad Company's contribution margin ratio would be

A. 36%

B. 34%

C. 69%

D. 64%