Final answer:
Organisms are adapted to their environment when they possess heritable traits that enhance both their survival and reproductive success. These advantageous traits are passed onto future generations, leading to adaptive evolution, which is driven by the mechanism of natural selection.
Step-by-step explanation:
Charles Darwin, alongside Alfred Russel Wallace, developed the theory of natural selection which is a fundamental mechanism of evolution. According to their observations, Darwin proposed that organisms are adapted to their environment when they possess heritable traits that enhance their survival and reproductive success. This process was described as 'descent with modification'. Organisms that have inheritable traits allowing them to better utilize resources or survive environmental pressures tend to leave more offspring. As these advantageous traits are passed onto the next generation, they become more prevalent within the population over time, leading to adaptive evolution.
Therefore, the correct answer to the student's question is 4) heritable traits that enhance their survival and reproductive success in the local environment. Non-heritable traits do not play a role in natural selection since they cannot be passed down to the next generation and consequently, do not contribute to evolution.