You Work as a Marketing Analyst for a Pharmaceutical Firm

You work as a marketing analyst for a pharmaceutical firm, and you are trying to gather information about the marginal cost of production for a competing firm. You know that they have a patent on a popular medication that sells for $20 per dose, and you believe the elasticity of demand for this product is roughly -4. Assuming the competing firm acts as a profit-maximizing monopolist, what is the competing firm's approximate marginal cost of production?

A) $10 per dose
B) $12.50 per dose
C) $15 per dose
D) $20 per dose