A thesaurus lists words in alphabetical order which is why the word "coax" would come after the word, "coat" because the last letter "x" in coax comes after the last letter "t" in coat.
B is incorrect because the "x" in coax comes after the "s" in coast so coax would come after coast not before. C is incorrect because blue begins with b and will definitely come after coax which starts with c.
Finally D is incorrect as well because the "a" in coax comes before the "i" in coin in the alphabet so coax will come before coin not after.
