Respuesta :
B is the correct answer. In MLA style, for both titles and subtitles, you must capitalise all nouns, verbs, pronouns, adjectives, adverbs and subordinating conjunctions. Articles, co ordinating conjunctions, prepositions and to-infinitives are not capitalised.
And the correct answer B. (of the) should not have any capital letters
B.) Parrots of the Wild: A Natural History of the World's Most Captivating Birds
hope that helped. :)