In the Section "Investigating Life: Solar-Powered Sea Slugs",chloroplast DNA Encodes

In the section "Investigating Life: Solar-Powered Sea Slugs",chloroplast DNA encodes less than 10% of the proteins required for photosynthesis;the remaining proteins are encoded by DNA in plant nuclei.Elysia chlorotica sea slugs are able to photosynthesize with chloroplasts from the algae they consume.How did the scientists rule out that the chloroplasts could function outside of a host cell?

A) The chloroplast chromosomes were missing a key gene for photosystem II.
B) They shined light on the chloroplasts and measured oxygen production.
C) They found the algal photosystem II gene in the sea slug chromosomes.
D) They did NOT find the photosystem II gene in the puffer fish chromosomes.
E) They injected the chloroplasts into a heterotrophic bacteria and successfully performed photosynthesis.