Please help, I Will rate!!! :)

Steve's shop sells seashells by the seashore. Steve buys shells from local collectors for an average price of $0.50 per shell (Hint: unit price is $0.50). Steve sells on average 1,000 shells each month (Hint: monthly demand is 1,000 shells). Each time he orders shells from collectors; there is a $20 shipping and handling fee. Steve estimates a unit holding (carrying) cost of $0.50 per shell per year (many of them get broken if held in inventory too long). How often should Steve order seashells? (Hint: Once you calculate the order frequency, you can answer this question easily.) Approximately once a week Approximately once a month Approximately every other month (by-monthly) Cannot determine from the above information