Please explain number 7!!!

In deciding which product to emphasize, Gadgets Inc., should focus on the line that has the highest: A. profit per unit of product. B. contribution margin per unit of the constraint. C. contribution margin ratio. D. selling price per unit of product. Signature Corporation has three product lines: silver, gold, and platinum. All three products have a positive contribution margin, but the gold line has an operating loss. Management is considering discontinuing the product. If management decides to discontinue the gold line, then which of the following was (is) true? A. Total cost savings exceeded the lost revenues from discontinuing the line. B. Lost revenues exceeded the cost savings from discontinuing the line C. Operating income will not change. D. Not enough information is present to make that determination Thematics Publishing produces 10,000 binders each year. Each binder has a variable cost of $17 and total fixed costs of $110,000 per year. The binders can be purchased from an outside supplier for $20 each. The production space will remain idle, but fixed costs can be reduced by 30%. The annual impact of purchasing the binders will be to: A. increase operating income by $3,000 B. increase operating income by $47,000 C. decrease operating income by $3,000 D. decrease operating income by 447,000