a scientist randomly divided a group of 100 lab rats into two groups of 50. one group was fed regular rat chow while the other was fed the same amount of rat chow with added DDT. Both groups were housed in the same room with the same environmental conditions. At the end of the experiment, rats were weighed and the mean difference calculated... What variable(s) was/ were manipulated by the scientist?

DDT

Explanation:

(DDT) may be defined as the colorless chemical used as an insecticide in the field. But the DDT is accumulated in the environment and cause pollution. The experiment given in the question explains the effect of DDT. Here, the manipulated variable or the treatment variable because its value is changed in the experiment. The rat is treated with the DDT and its effect is noticed in the experiment. The experiment depends on the value of DDT and acts as the manipulated variable