The HeLa cells were originally cancer cells that were sampled when doctors tried to treat the cancer. Later they found that those cells never died, but continued to grow. That is there main purpose in research because they are an immortal strain. They became a very powerful tool in cancer research.
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.
