What is the primary focus of Darwin's book "On the Origin of the Species"?

Darwin's "On the Origin of the Species" primarily emphasizes the concept of natural selection as the mechanism behind evolution and the diversity of organisms. In the book, Darwin meticulously lays out the concept that individuals within a species exhibit variations, and those traits that enhance survival and reproduction become more common in subsequent generations. This process leads to the gradual evolution of species over time.

While the concepts of speciation, variability, and survival strategies are essential elements in understanding evolution, they serve as supporting details within the broader framework of natural selection and how it drives the diversity of life. The focus on natural selection provides the scientific basis for understanding how species adapt to their environments and change over generations, ultimately leading to the rich tapestry of life observed on Earth. Thus, the correct answer encapsulates the central theme of Darwin’s groundbreaking work.