[my experiment proved beyond a doubt that vitamin c can reduce the severity of colds, because i controlled the experiment carefully for every possible confounding variable. choose the correct answer below. a. the statement does not make sense because it is not always easy to discover confounding variables. b. the statement makes sense because every possible confounding variable can be eliminated through careful study. c. the statement makes sense because confounding variables are the only reason an experiment's results could be doubted. d. the statement does not make sense because confounding variables would not affect the reliability of the experiment.