All other things constant or nothing else changes Winona is a research assistant for her favorite biology professor, Dr. Diaz. Dr. Diaz is interested in studying the effects of feeding a certain chemical to rats to see how it affects their appetites. Winona knows from her economics class that to isolate the effects of a particular phenomenon, all other things must remain the same. In Latin, this is referred to as . In order to keep all other things the same and isolate the effects of one particular variable in the biology experiment, Winona will want to do which of the following?

a. Avoid drawing conclusions after one trial.
b. Offer the same type of food to the rats in each trial.
c. Make sure all tested rats are the same age.