Question

what key feature indicates that mitochondria and chloroplasts were once independent cells? they have their own dna. they both lack a membrane. they are identical dna to host cells.

Explanation:

The endosymbiotic theory suggests that mitochondria and chloroplasts were once independent prokaryotic cells. A key piece of evidence is that they have their own DNA (similar to prokaryotes). The option "They both lack a membrane" is incorrect as they have membranes. The option "They are identical DNA to host cells" is incorrect because their DNA is distinct from the host cell's nuclear DNA.

Answer:

A. They have their own DNA.