according to the endosymbiotic theory, which cellular process was involved in the evolution of mitochondria…

Brief Explanations:

The endosymbiotic theory posits that mitochondria and chloroplasts originated from prokaryotic cells that were engulfed by a host cell through endosymbiosis. Symbiosis is a general term for close - living relationships, phagocytosis is the process of a cell engulfing particles, and photosynthesis is the process of converting light energy into chemical energy. Endosymbiosis specifically describes the relationship that led to the evolution of mitochondria and chloroplasts.

Answer:

C. endosymbiosis