Natural selection is a process by which organisms that are better adapted to their environment tend toincrease in size. migrate. evolve new traits. survive.

survive

Natural selection is the process of differential survival and reproduction of individuals, because of the differences in the phenotypic traits. Some organisms which have favorable phenotypic traits support their the survival against the changing environmental conditions. These survived organisms later on attains the chance to reproduce and grow in number.  Charles Darwin gave the example of beetles. The two beetle populations exhibiting green and red color being living on grass. The green beetle population color resembling the color of grass remained undetected by crows whereas, the red beetles were easily identified and eaten up by crows. Therefore, the presence of green color was the phenotypic advantage for green beetles, hence favored their survival.  

the answer to your question is:

c. complementary base-pairing

enhanced global partnerships and exploration capabilities may advance international preparedness for protecting the earth from catastrophic events such as some asteroid strikes, advancing collaborative research on space weather and protecting spacecraft by developing new means for space debris removal.