Question

____ is a process by which organisms with characteristics suited to the environment will survive and reproduce.

Answer 1

The question is asking us to fill in the gap in the following phrase: (gap) is a process by which organisms with characteristics suited to the environment will survive and reproduce. The keyword here is "suited to the environment" - this suggests that other organisms will not survive and reproduce. This is known in biology as "natural selection" - also known as "survival of the fittest"

Answer 2

The correct answer is the natural selection.

Natural selection if one of the four mechanisms of evolution. Essentially, all of these four mechanisms, including the natural selection, work trough changing the frequencies of genetic variants (most often alleles) in a population. The alleles that bring its holder advantage over the other individuals in the population that do not possess this allele are going to be favored by the natural selection and passed down to the next generation. The bigger the advantage of an allele is, the quicker is it going to be recognized and selected by the natural selection.