Lynn Margulis developed the endosymbiont theory to explain the evolution of certain eukaryotic organelles, such as chloroplasts and mitochondria. According to this theory, which of these events occurred to an ancient prokaryotic cell?
A. Mutations caused the cell's DNA to direct the synthesis of new organelles.
B. The cell nucleus divided and changed to form other types of organelles.
C. The cell took in another ancient prokaryotic cell, which began living inside it.
D. The cell membrane divided and changed to form new types of organelles.