The correct answer is B. The sentence is incomplete because it lacks a complete predicate.
Explanation:
In grammar, for a sentence to be complete it requires a subject which is the agent that performs the action and a predicate which is the verb or main action and in some cases direct or indirect objects which are the agents or object directly or indirectly affected by the verb. In the case of the sentence "The pirate who sailed his ship in the Atlantic Ocean pilfering from British naval ships and irritating the British navy" this sentence contains only a subject as all the words included describe who the pirate was but do not tell which action the pirate performed. This means this sentence lacks a predicate as it does not contain a verb or any other words related to it. Thus, the best evaluation of the sentence is "the sentence is incomplete because it lacks a complete predicate".
