Final answer:
According to the theory of Relative Purchasing Power Parity, if the U.S. inflation rate is 4% higher than Canada's, the U.S. dollar should depreciate by that amount. Thus, the current exchange rate should be approximately $0.96/C$1.
Step-by-step explanation:
The theory of Relative Purchasing Power Parity (PPP) suggests that the change in the nominal exchange rate between two countries' currencies over a certain period should be equal to the difference in the countries' inflation rates over the same period. If the inflation rate in the U.S. has been 4% greater than that in Canada over the last year, and if one year ago the spot exchange rate was $1/C$1, then according to Relative PPP, the U.S. dollar should have depreciated by approximately 4% against the Canadian dollar. Hence, the current exchange rate should be approximately $0.96/C$1, as the U.S. dollar would now buy 4% less Canadian currency.