What theory explains the evolution of eukaryotic cells from a symbiotic relationship?

The theory that explains the evolution of eukaryotic cells from a symbiotic relationship is the endosymbiosis theory. This theory postulates that eukaryotic cells, which are more complex than prokaryotic cells, originated through a process whereby certain prokaryotic cells began living inside larger host cells in a mutually beneficial arrangement. Over time, these engulfed prokaryotes evolved into organelles such as mitochondria and chloroplasts, which are essential for the function of eukaryotic cells.

Endosymbiosis is supported by various lines of evidence, including the presence of their own DNA in mitochondria and chloroplasts, which is similar to prokaryotic DNA, as well as similarities in the size and structure of these organelles to certain prokaryotic cells. This underscores the idea that complex life forms arose from simpler organisms living in close association with one another, leading to increased complexity and functionality in cells.

The other options do not adequately describe the specific mechanism by which eukaryotic cells originated. Mutualism focuses on interactions between species that are mutually beneficial but does not address the cellular evolution aspect. Cellular evolution theory is more general and does not specifically entail the process by which e