Question

chloroplasts, the organelles that allow plants to perform photosynthesis, are a type of plastid. scientists currently believe that plastids were originally independent organisms closely resembling modern ___ commonly known as blue - green algae. which choice completes the text so that it conforms to the conventions of standard english? a cyanobacteria: more b cyanobacteria. more c cyanobacteria; more d cyanobacteria, more

Explanation:

In standard English, a colon is used to introduce an explanation or elaboration. Here, "cyanobacteria: more commonly known as blue - green algae" is the correct usage to explain what cyanobacteria are also called. A period after "cyanobacteria" (option B) makes the second part a run - on. A semicolon (option C) is used to separate two independent clauses, which is not appropriate here. No punctuation (option D) makes the sentence unclear.

Answer:

A. cyanobacteria: more