The best answer in this case is C, "the researchers applied creativity to solve a problem in running an experiment".
Distributing the computing load across the global community by sharing processing power is a creative response to tackle the challenge in simulating protein folding for the experiment. This does not change or reduce the scientific merits of the experiment, so we can discount the first two answers (a & b). Answer d talks about well established scientific techniques, although the question wasn't really centered around the specific techniques, so it's not as relevant an answer as C.
The two cells that result from a single cell need to have the same amount of genetic material as the initial cell, therefore the DNA needs to be duplicated before the cell divides.
The sister chromatids are attached together so that during anaphase the daugther cells will receive the same chromosomes
Cardiovascular Diseases refers to a group of illnesses, disorders and in some cases serious abnormalities that affect the heart and blood vessels.
