An experiment will be conducted to determine whether children learn their multiplication facts better by practicing with flash cards or by practicing on a computer. Children who volunteer for the experiment will be randomly assigned to one of the two treatments. Because the children's gender may affect the outcome, there will be blocking by gender. After practice, the children will be given a test on their multiplication facts. Why will it be impossible to conduct a double-blind experiment? (A) The experimenter will know whether the child is a boy or a girl and whether he or she used flash cards or the computer. (B) The child will know whether he or she is a boy or a girl. (C) The child will know whether he or she used flash cards or the computer. (D) The person who grades the tests will know whether the child was a boy or a girl. (E) The person who grades the tests will know whether the child used flash cards or the computer