Ascientist is trying to determine whether the use of cell phone contributes to brain cancer. for his study, he compares the medical records of subjects who have been diagnosed with brain cancer to the records of healthy subjects. what is the most significant weakness in this type of study?

Many body systems work together for proper functioning of the body and to maintain internal homeostasis. the works to break down food eaten before exercising. the takes in the nutrients obtained from the food. the body sweats as a mechanism to cool off, because the is working to flush out toxins.