Which of the following organisms reproduces through fragmentation?

Fragmentation is a form of asexual reproduction where an organism splits into parts, and each part can regenerate into a complete organism. In the context of the given options, flatworms are known for their ability to reproduce through this method. When a flatworm is cut into segments, each segment can regenerate into a new, complete flatworm, showcasing their remarkable regenerative abilities.

Starfish also exhibit a form of regeneration and can reproduce asexually through this method, but they typically require a portion of the central disk along with an arm to regenerate. Lizards utilize a technique known as parthenogenesis in some species, while crabs reproduce primarily through sexual means, laying eggs that develop into larvae. Thus, in this case, flatworms are the most representative example of organisms that reproduce through fragmentation.