Which one of the following sentences is punctuated correctly?
a. the sea calmed; but no boats, left shore.
b. the sea, calmed, but no boats, left shore.
c. the sea calmed but no boats left shore.
d. the sea calmed, but no boats left shore

C. The comma needs to be before the conjunctive adverb in a sentence. 

Conclusion is the answer

Allusion and illusion. an allusion is an indirect reference, whereas an illusion is something that is unreal or incorrect. each of the nouns has a related verb form: allude “to refer indirectly to,” and illude (not a very common word), which may mean “to delude or deceive” or “to subject to an illusion.”