Parts A, B, C, D, E, and F are included in the same 1 question (you can skip F if it's too much). Thank you in advance!

Hilern Inc. recorded the following data for the past month: For the past month, fixed manufacturing overhead was $4,000 and the selling and administrative expense was $3,600. At the beginning of the month, the company had 300 units in inventory. During the month, 2,000 units were produced and 2,100 units were sold at a selling price of $14 per unit. Required: (A) Compute the per-unit product cost using absorption costing. (B) What is the operating income (loss) using absorption costing? (C) Compute the per-unit product cost using variable costing. (D) What is the operating income (loss) using variable costing? (E) Discuss the typical reasons why a company would have inventory on-hand. (F) What is a Just-in-Time inventory system? Provide some examples of companies have adopted JIT and discuss possible reasons they would for using this inventory policy system