Option 1 -> Inevitable means unavoidable or certain to happen, which fits when a team lacks preparation.
Option 2 -> Avoidable means preventable, which contradicts the idea that lack of preparation led to failure.
Option 3 -> Improbable means unlikely, but failure would be likely (not unlikely) when a team lacks preparation.
Option 4 -> Optional means a choice, which doesn't logically describe failure as an outcome.
Hence, Option 1: inevitable -> The word "inevitable" correctly conveys that the team's failure was unavoidable or bound to happen due to their lack of preparation, despite individual efforts to prevent it. -> correct