By going option choices we can see that either statement I or III is an opening sentence. But in statement I, it is given that "the economy’s performance in expenditure terms was even poorer with real GDP" i.e. there should be preceding sentence that's the whole reason of comparison. The contraction that is being talked in statement IV is mentioned in statement II. Hence, we can say that statement II and IV is a mandatory pair. Therefore, we can say that option C is the correct answer.