The endosymbiotic theory states that chloroplasts and mitochondria evolved as a result of
a prokaryotic cell engulfing a bacterial cell.
a eukaryotic cell engulfing a bacterial cell.
a bacterial cell engulfing a prokaryotic cell.
a bacterial cell engulfing a eukaryotic cell.

A Eukaryotic cell engulfing a bacterial cell.

You may want to know that the bacteria which used to photosynthesise , after they have been engulfed by an eukaryotic cell , they evolved into Chloroplasts .
However for the bacteria which used to respire , they have evolved into mitochondria.

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