During an experiment to determine if people with more symmetrical body features have a lower incidence of disease, a researcher first measures the length of several bones in the subject's hands and arms. The device used to measure length does not display a readout of the measurement taken. Instead, a wire connects the measuring device to a computer that records the data. The computer monitor is kept out of sight of the subject and the researcher. Why is such an elaborate device used?a. So that the subject will not know if he or she is part of the control group. b. So that the experiment will be repeatable. c. So that the subject will not be injured by the experiment. d. So that the identity of the subject will remain anonymous. e. So that the measurements are not biased by the researcher.