Identify the other key structures that indicate the probable origin of a chloroplast

Chroloplasts Acts as a main role in photosynthesis.Chloroplasts likely orginated from engulfed "prokaryotes" that once lived as independent organisms. They are also considered to be originated from "cyanobacteria" through endosymbiosis—when a eukaryotic cell engulfed a photosynthesizing cyanobacterium that became a permanent resident in the cell.

Nimbostratus is the correct answer.
explanation: nimbostratus clouds are the type of clouds that are mostly likely present on gray, rainy day. these clouds produce continuous rain, snow and there is no thundering or lightening either.