Generally, scratches and heavy wear will diminish the appraisal of a musical instrument ______ when that instrument was owned by a virtuoso like Niccolò Paganini, such imperfections can verify authenticity and increase value.
Which choice completes the text so that it conforms to the conventions of Standard English?
value
value,
value but
value, but
Correct Answer: D
Choice D is the best answer. The sentence consists of two independent clauses presenting contrasting ideas regarding value. These clauses are correctly joined by a comma and the coordinating conjunction "but."
Choice A is incorrect because it fuses two independent clauses without punctuation. Choice B is incorrect because a comma alone is insufficient to join two independent clauses (comma splice). Choice C is incorrect because it misses the comma required before the coordinating conjunction "but" when joining independent clauses.