Port Corporation sells item X-100. Purchases, sales and costs of item X-100 for the last quarter of 2019 follow: Date Units Purchased Units Sold Unit Cost October 1 500 $4.00 October 15 300 $4.10 October 30 600 November 10 400 $4.20 November 25 500 December 5 800 $3.90 December 20 700 The selling price for all units sold in the quarter was $10.00. REQUIRED: 1. Assume the company uses a periodic inventory system. Calculate the cost of goods sold for the last quarter of 2019 using the FIFO method of cost valuation. (2 marks) 2. Prepare the journal entry to record the sale on October 30th (on account). Assume the company uses a perpetual inventory system and FIFO method of valuation. (2 marks) 3. Prepare the journal entry to record the sale on October 30th (on account). Assume the company uses a periodic inventory system and FIFO method of valuation. (1 mark) 4. This question does not relate to the data above. Ignore all of the above information. Required: If ANY company wants to maximize gross margin and, assuming the unit cost of inventory purchases will always increase, which inventory cost valuation method should that company choose? Include a brief one-sentence explanation. (2 marks)