(C)suggest the reduction of software prices for decreasing the incentive for pirating, and still others call (E)suggest reducing software prices to decrease the incentive for pirating, and still others are calling
same as majority of you, i also confuse about tense problem that is presented here by "call" and " are calling". Usually, ETS emphasizes the parallelism by identical formulation, but here it's not so. However, there is an obvious error in choice c. "the reduction of software prices for decreasing the incentive " is unidiomatic. Here, it's nothing but a small trick that ETS plays.