Explanation
Correct answer: D.
Choice D is the best answer. The convention being tested is the use of punctuation within and between sentences. In this choice, the colon correctly introduces the name of the instrument (the flute) that novel audio technologies allowed to be added to jazz and swing. In addition, the period is used to correctly mark the boundary between one sentence ("In…flute") and another ("A relatively…greats").
Why the other choices are wrong
Choice A
Choice A is incorrect because it results in a comma splice. A comma can’t be used in this way to join two main clauses ("In…quiet instrument" and "its…greats").
Choice B
Choice B is incorrect. In standard English, it’s unconventional to form a sentence in this way with two uncoordinated subjects ("the flute" and "its full range of sound"), and the lack of a clear main subject results in an awkwardly constructed and confusing sentence.
Choice C
Choice C is incorrect. In standard English, it’s unconventional to form an independent clause in this way with two uncoordinated subjects ("the flute" and "its full range of sound"), and the lack of a clear main subject results in an awkwardly constructed and confusing clause.