Final answer:
In 'To Kill a Mockingbird', the mockingbird symbolizes innocence and beauty, represented by characters who are harmless and kind, yet are subjected to cruelty and injustice.
Step-by-step explanation:
In Harper Lee's To Kill a Mockingbird, the mockingbird comes to symbolize innocence and beauty. The notion is presented through the advice given by Atticus Finch to his children when he says that it's a sin to kill a mockingbird. This is because mockingbirds do nothing but provide pleasure with their singing; they don't do any harm to anyone. In the context of the novel, this symbolism extends to characters such as Tom Robinson and Boo Radley, who, like the birds, are innocent and do not intend harm, yet they suffer at the hands of others. Thus, option a) Innocence and beauty is the correct answer to what the mockingbird symbolizes in the novel.