The initial causes of serious accidents in space shuttle missions so far have not been flaws in the advanced technology used in the space shuttles. Rather, the causes have been attributed to human error. Unfortunately, human error is bound to occur at some point. Which one of the following is most strongly supported by the statements above? ['Space shuttle missions are not worth the risk.', 'As the technology used in space shuttles improves, it will eventually overcome human error.', 'If space shuttle missions continue, a serious accident is not improbable.', 'No serious accident will be caused in the future by some flaw in the advanced technology used in space shuttles.']