ANSWER: b.15
EXPLANATION: The marginal cost to produce two jackets is $15. The definition of Marginal Cost is the additional cost that is involved to produce one additional unit of product or service. In this table, the cost of producing the first jacket was $18 and the total cost of producing two jackets is $33. So, subtracting the total cost from the cost of producing the first jacket we get, $33 - $18 = $15, which is the marginal cost.