Final answer:
The fundamental mechanism of evolution in response to environmental influence is natural selection, which drives the differential survival and reproduction of organisms.
Step-by-step explanation:
The fundamental mechanism of evolution whereby an organism changes on its own as a result of environmental influence is called natural selection. This process involves the differential survival and reproduction of individuals due to differences in phenotype, which can be influenced by inherited traits. It is a key mechanism by which evolution operates, leading to the adaptation of organisms to their environment over time.
Mutations and gene flow, which include migration, also play a significant role in introducing new genetic variation into a population. While mutations are random changes in the DNA sequence, gene flow occurs when individuals migrate into or out of a population, bringing new alleles with them. This genetic variation is essential for natural selection to act upon. The fundamental mechanism of evolution influenced by the environment is natural selection (d).