Information from the accounting system revealed the following:

Day 1 Day 2 Day 3 Day 4 Day 5 .

Materials $20,000 $19,000 $21,500 $21,000 $21,000

Electricity 2,500 3,000 4,000 4,900 5,200

Maintenance 4,000 3,900 4,000 3,900 4,200

Total costs $26,500 $25,900 $29,500 $29,800 $30,400

Pounds produced 10,000 9,000 10,000 10,000 10,000

Cost per unit $ 2.65 $ 2.88 $ 2.95 $ 2.98 $ 3.04

Which of the following statements best interprets the information?

A. The total costs are out of control.

B. The total costs have steadily increased because of higher electricity costs.

C. Electricity costs have steadily increased because of lack of maintenance.

D. The unit costs reveal a significant operating problem.