The cost of production report for August shows conversion costs for 5,000 gallons, 70% complete, to be $2,450. The conversion cost per equivalent unit in July was $0.75. Which of the following best describes the change in the conversion costs between the two months?

a. The conversion costs increased by $0.05 per unit, indicating an improvement.

b. The conversion costs increased by $160 overall, indicating an unfavorable change.

c. The conversion costs decreased by $0.05 per unit, indicating an improvement.

d. The conversion costs decreased by $0.05 per unit, indicating an unfavorable change.