4. The accounting records of the National Corp. show the following: Selling and Administrative Expense $ 10,000 Sales Discounts 1,000 Cost of Goods Sold 70,000 Sales Revenue 100,000 Income Tax 5,000 Interest and Other Expenses 1000 The gross profit for the National Corp. is: a. $18000 b. $19,000 C. $29,000 r1 $30 non