Caffeine is a chemical compound that stimulates the human central nervous system. Research into the effects of caffeine has been performed by a myriad of companies from different places around the world, and new evidence is published every few months. High caffeine intakes cause nervousness and insomnia in some subjects while drowsiness and repose are experienced by others. Furthermore, some people report a laxative effect while in others it can result in constipation.
Which of the following conclusions is most strongly supported by the information above?
(A) Since there is not enough consistency with regards to results, research of such a chemical is not advantageous and should be discontinued.
(B) The individuality of human subjects creates difficulty when attempting to form a definitive judgement about the symptoms of caffeine.
(C) Caffeine does not affect the central nervous system in all people and, therefore, physiological symptoms can also vary.
(D) Caffeine can act as an addictive substance causing unpleasant side effects and harm to the human body's basic functions.
(E) To conduct more accurate research, examinations should be carried out on larger test groups.