Cigarettes contain many substances that are known to cause cancer and are called carcinogens. These substances are added to provide flavors and make smoking to feel more enjoyable. Because of that, the answer is that cigarette manufacturers purposely add carcinogens to cigarettes in order to give them a particular flavor.
I believe the correct answer to the question is D. This answer choice makes the most sense given the context. Also, since RNA is less stable than DNA, it mutates more often.
