D.The Library of Congress appointed W. S. Merwin to the prestigious, respected position of Poet Laureate Consultant.
Coordinate adjectives are adjectives that come before the noun that they describe. The coordinate adjectives in this sentence are prestigious and respected. They describe the position. Options A and C are both wrong because they use commas to separate the words of the title of the position "Poet Laureate Consultant", not the coordinate adjective. When using commas with coordinate adjectives, you only put a comma in to separate the adjectives from each other not from the noun. Option B is wrong because it uses a comma after respected which separates the adjective from the noun it describes.
