This is a common feature of plastids and mitochondria

The correct option is All of the above.

To understand why this is correct, let we analyze the common structural and genetic features shared by both plastids (such as chloroplasts) and mitochondria:
1. Presence of double-stranded DNA (dsDNA): Both plastids and mitochondria are semi-autonomous organelles. They contain their own extrachromosomal, circular, double-stranded DNA, which allows them to replicate independently of the nucleus and synthesize some of their own proteins.
2. Presence of 70S ribosomes: Reflecting their prokaryotic origin (explained by the endosymbiotic theory), both organelles contain 70S ribosomes, which are characteristic of prokaryotic cells, rather than the 80S ribosomes found in the surrounding eukaryotic cytoplasm.
3. Double-membranous structure: Both mitochondria and plastids are enveloped by two distinct membranes: an outer membrane and an inner membrane, with an intermembrane space between them.

Since both organelles possess dsDNA, contain 70S ribosomes, and are double-membranous cell organelles, all the individual statements are correct. Therefore, the comprehensive option "All of the above" is the correct choice.