Q1. The answer is c. a mechanism of evolution.
Natural selection is the differences in survival and reproduction as the consequence of differences in phenotypes. According to Darwin's theory of evolution, natural selection is the only factor that affects a frequency of different variations and it is the only mechanism of evolution.
Q2. The answer is c. interactions between individuals.
Organisms interact with other organisms or abiotic factors in some system. The interaction between individuals affects their regular distribution. For example, if two groups are in competition for resources, to maximize resource utilization, they will probably live in different areas or will defend territory. Also, some symbiotic organisms are expect to be distributed similarly.
