When a pharmaceutical firm holds a patent on a drug, that firm is the only seller legally

permitted to sell that drug. Suppose Pfizer holds a patent on drug X, but this patent will

expire at the end of the year. Following the expiration of the patent, the price elasticity of

demand for drug X from Pfizer will most likely because of a

change in .

(a) Increase; the availability of close substitutes

(b) Increase; the mobility of inputs

(c) Decrease; the availability of close substitutes

(d) Decrease; the mobility of inputs