Question #N377

A new study suggests that children who spend time outdoors in nature may benefit from improved cognitive and social development. The study found that children in the study group who spent at least one hour per day in a natural setting performed better on tests that measure attention and problem-solving skills than those who spent less time in nature. The researchers believe that the benefits of spending time in nature may be related to the increased exposure to sensory stimuli and the opportunity for unstructured play and exploration. "Because these results are promising," say the researchers, "additional studies need to be conducted to determine the exact mechanisms by which nature may enhance cognitive and social development."

Which choice best combines the two sentences at the end of the passage into a single sentence that is grammatically correct and avoids redundancy?
A. Because these results are promising, the researchers say, additional studies need to be conducted to determine the exact mechanisms by which nature may enhance cognitive and social development.
B. These results are promising, say the researchers, so additional studies need to be conducted to determine the exact mechanisms by which nature may enhance cognitive and social development.
C. These results are promising, the researchers say, and additional studies need to be conducted to determine the exact mechanisms by which nature may enhance cognitive and social development.
D. Because these results are promising, additional studies need to be conducted to determine the exact mechanisms by which nature may enhance cognitive and social development, the researchers say.