A. is incorrect because diesease is unrelated. War casualties do not equal diesease in population.
B. is incorrect because more deaths does not necessarily mean more battles. Infact, usually the opposite, because a side could be forced to surrender if it doesn't have enough troops.
C. is incorrect because elections would carry on just the same whether or not war casualties were high.
He wanted to build up the nation's army and navy is the statement among the statements given in the question that was one of the policy changes Thomas Jefferson made when he became president. The correct option among all the options given in the question is the last option or option "D".
