The cause of the wreck of the ship Edmund Fitzgeraid in a severe storm on lake Superior is still unknown , when the sunken wreckage of the vessel was round , searchers discovered the hull in two pieces lying close together , The storm's violent waves would have caused separate pieces floating even briefly on the surface to drift apart. Therefore, the breakup of the hull can be ruled out as the cause of the sinking.
Which of the following is an assumption on which the argument dipends?