The correct answer is surrounded by two membranes.
A chloroplast refers to a kind of organelle called plastid, featured by a high amount of chlorophyll and two membranes. Chloroplasts play an essential role in the process of photosynthesis.
On the other hand, mitochondria refer to an organelle found in huge concentrations in the majority of the cells, in which the biochemical methods of energy production and respiration takes place. It exhibits a double membrane. Both the chloroplasts and mitochondria exhibit their own genetic material, that is, DNA.