What does the study of "recapitulation" focus on in organisms?

The study of "recapitulation" focuses on the idea that the development of an individual organism (ontogeny) follows a path that resembles the evolutionary history of that organism's species (phylogeny). This concept, often summarized as "ontogeny recapitulates phylogeny," highlights the idea that during its development, an organism passes through stages that resemble the adult forms of its evolutionary ancestors.

Focusing on the similarity of structures in similar positions during various developmental stages of different organisms aligns with this idea. For example, embryos of different vertebrates exhibit similar features, such as gill slits and tails, which reflect their shared evolutionary background, even if those features change or disappear as development progresses. This commonality in embryonic development serves as evidence for evolutionary relationships among species, emphasizing structural homology and developmental biology.

In contrast, the other choices may explore different aspects of biological study but do not encapsulate the essence of recapitulation clearly.