The symptoms that United States President Zachary Taylor began showing five days before his death are consistent with arsenic poisoning. Recent examination of Taylor's bones, however, revealed levels of arsenic comparable to those found in the bones of Taylor's contemporaries. These levels are much lower than the levels of arsenic that remain in the bones of arsenic poisoning victims who live for more than a day after ingesting a lethal dose of the poison.

Which of the following is most strongly supported by the statements given?