Final answer:
The correctly capitalized book title in the MLA style is 'To Kill a Mockingbird'. Most words in book titles are capitalized, except for prepositions and coordinating conjunctions.
Step-by-step explanation:
The correctly capitalized book title is To Kill a Mockingbird. In this title, the first word and all major words are capitalized. For example, The and and are not capitalized unless they are the first word or last word in the title.
According to the MLA style for capitalization in titles and subtitles, the correct capitalization among the options provided is: b. To Kill a Mockingbird. In book titles, most words are capitalized, including the first and last words of the title and all the nouns, pronouns, verbs, adjectives, adverbs, and subordinate conjunctions. Prepositions and coordinating conjunctions are the only words that are typically lower case, unless they are the first or last words of the title. Using this guideline, 'To Kill a Mockingbird' is the only title correctly capitalized.
Learn more about Title Capitalization