A retailer uses the cost method to value trading stock and had an opening stock value of $120,000. During the year it purchased an additional $150,000 of trading stock. The closing stock had a value of $130,000. It derived $480,000 of sales income from selling trading stock. What is the Retailer's annual gross income for the income year? A. Annual gross income is $320,000 B. Annual gross income is $240,000 C. Annual gross income is $480,000 D. Annual gross income is $510,000