If the international Fisher effect $($IFE$)$ did not hold based on historical data, this would suggest that:$$

a$.$some corporations with excess cash could have generated profits on average from covered interest arbitrage.

b$.$some corporations with excess cash could have generated higher profits on average from foreign short$-$term investments than from domestic short$-$term investments.

c$.$some corporations with excess cash could lock in a guaranteed higher return on future foreign short$-$term investments.

d$.$most corporations that consistently invest in foreign short$-$term investments would have generated the same profits $($on average$)$ as from domestic short$-$term investments.