The principle of natural selection, as described by Darwin in 'The Origin of Species', posits that organisms with traits that are advantageous for their environment are more likely to survive and reproduce, passing those traits on to the next generation. This process leads to the evolution of species over time. Option B correctly captures this principle by emphasizing the role of adaptation to the environment in survival and reproduction. Option A is incorrect because it ignores the role of the environment in selecting for advantageous traits. Option C is incorrect because it contradicts the principle of natural selection by suggesting all species have an equal chance of survival, regardless of their adaptations. Option D is incorrect because it misrepresents evolution as a linear and progressive process, whereas natural selection does not necessarily lead to increased complexity.