Under the Perpetual Inventory System What Is the Correct Entry

Under the perpetual inventory system what is the correct entry to record the cost of the sale of 2 electric guitars sold to a customer at $550 per guitar including GST? The guitars were originally purchased on credit at $250 each plus GST of $25 per guitar.

A) Debit cost of sales $1 100; credit sales $1 100
B) Debit cost of sales $500; credit inventory $500
C) Debit cost of sales $1 000; credit inventory $1 000
D) Debit cost of sales $500,debit GST outlays $50; credit inventory $550