What is the main idea behind the theory of evolution?

The main idea behind the theory of evolution is that species change over time through a process known as natural selection. This concept, introduced by Charles Darwin, suggests that organisms with traits that are advantageous for survival and reproduction in their environments are more likely to pass on those traits to the next generation. Over long periods, this process can lead to significant changes in the characteristics of a species, potentially resulting in the emergence of new species altogether. This theory helps explain the diversity of life on Earth and how organisms adapt to their environments based on selective pressures such as competition, predation, and climate changes.

The other options do not align with the well-supported scientific understanding of evolution. For example, claiming that species remain unchanged or do not evolve contradicts the extensive evidence that shows species adapt and change over time due to environmental influences. Additionally, the idea that species are created in isolation does not account for the continual genetic exchange and adaptation seen in nature. Hence, the idea of changing species through natural selection captures the essence of evolutionary theory accurately.