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 host cell. Prokaryotes have their own DNA. The discovery of DNA in mitochondria supports this theory because it suggests that mitochondria have a characteristic (own DNA) similar to prokaryotes. DNA in the cell nucleus is typical of eukaryotic cells and does not support the endosymbiotic theory. Ribosomes do not contain DNA, and DNA in the cytoplasm in a eukaryotic cell is not a key piece of evidence for endosymbiosis as the DNA in mitochondria is more related to the prokaryotic - like nature of mitochondria.

Answer:

A. DNA in mitochondria