Answer:
A). Really increased the value of their house with that addition.
Step-by-step explanation:
As per the given options, the sentence that does not exemplify a complete sentence is displayed in option A as it doesn't offer a complete sentence. The sentence 'Really increased the value of their house with that addition' lacks the subject as it proposes a description but fails to answer the question 'who' or 'what' which symbolizes the absence of doer or subject in the sentence. As we know, a sentence is categorized as a complete sentence when it contains a subject followed by a predicate(includes verb and object that describes the subject, or its action) to proposes a complete thought. Since the first option lacks the subject who performs the action or is being described. Thus, option A illustrates an incomplete sentence.