Given a scientific passage and an answer, generate a question for the given answer.

Passage: Like mitochondria, plastids contain their own DNA. Therefore, according to endosymbiotic theory, plastids may also have evolved from ancient, free-living prokaryotes that invaded larger prokaryotic cells. If so, they allowed early eukaryotes to make food and produce oxygen. Answer: dna
Like mitochondria, plastids contain their own what?