CharCore mixes together wood chips and pine oil. After joint manufacturing costs of $$2,000$ have been incurred, the mixture separates into two products, granulated charcoal and methyl alcohol. At the split$-$off point, the granulated charcoal can be sold for $$5,000,$ and the alcohol can be sold for $$9,000.$ The charcoal can be further processed at a cost of $$6,000$ to make air filters, which can be sold for $$15,000.$ The alcohol can be further processed at a cost of $$7,000$ to make a cleaning solvent, which can be sold for $$14,000.$ In deciding whether to sell the products at the split$-$off point or process further, which of the following is the most relevant metric to use?

A$.$The variable costs that would be incurred in processing further

B$.$ The selling prices of the products at both the split$-$off point and after being processed further

C$.$ The difference in profit between selling at the split$-$off point and processing further

D$.$ The costs incurred to process further