The fill in the blank answer is increased
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.
Answer:
Algal blooms occur when algae multiply very quickly. Blooms can form in waters that are rich in the nutrients the algae need to grow, such as nitrogen, phosphorous, and iron. ... Blooms may become more frequent as the earth warms and the levels of nutrients in our waters increase.