Cindy's Toys Has an Average Inventory of 1,800 Teething Rings

Cindy's Toys has an average inventory of 1,800 teething rings. The carrying cost per unit per year is
5¢. Cindy places an order for 3,600 teething rings on the first of each month and the order cost is
$25. What are the total restocking costs under the current system?

A) $45
B) $90
C) $150
D) $164
E) $300