Complete the sentence.
The historian noted irony in the fact that developments considered _______ by people of that era are now viewed as having been _______.

Something that is “improbable” is unlikely to occur, and something that is “inevitable” is unavoidable and will definitely occur. If one were to insert these terms into the text, the sentence would read “The historian noted irony in the fact that developments considered improbable by people of that era are now viewed as having been inevitable.” “Irony” refers to a contrast between what is expected and what actually occurs. It is logical for the historian to perceive “irony” in the fact that what was once considered unlikely to occur is now seen as having been unavoidable.