Answer the question on the basis of the following cost data.

output Average Average variable

fixed cost cost

1 $50.00 $100.00

2 $25.00 $80.00

3 $16.67 $66.67

4 $12.50 $65.00

5 $10.00 $68.00

6 $8.37 $73.33

7 $7.14 $80.00

8 $6.25 $87.50

The marginal cost of the fifth unit of output is

A) $3.00

B) $62.00

C) $80.00

D) $78.00