Question

which discovery supported the endosymbiotic theory? dna in mitochondria dna in the cell nucleus dna in ribosomes dna in the cytoplasm

Explanation:

The endosymbiotic theory proposes that mitochondria and chloroplasts were once free - living prokaryotes that were engulfed by a larger cell. The presence of DNA in mitochondria supports this theory as it suggests that mitochondria have an independent genetic system, similar to prokaryotes. Nucleus DNA is part of the eukaryotic cell's main genome, ribosomes do not have DNA (they have rRNA), and while there is some DNA in the cytoplasm in the form of mitochondrial and chloroplast DNA, the key here is mitochondrial DNA specifically.

Answer:

DNA in mitochondria