Final answer:
The antecedent problem in the given sentence is that the reference of 'it' is unclear and could pertain to either the 'mirror' or the 'shelf', leading to the correct response being A. It could refer to the mirror or the shelf.
Step-by-step explanation:
The antecedent problem in the sentence 'He carefully placed the mirror on the shelf, but it shattered.' is addressed by identifying the unclear reference made by the pronoun 'it'. The correct answer is A. It could refer to the mirror or the shelf. The pronoun 'it' is singular and refers back to the noun it replaces, but the sentence may lead some readers to wonder whether the pronoun 'it' refers to the 'mirror' or the 'shelf'. This ambiguity can lead to confusion and typically should be avoided by ensuring pronouns clearly refer back to their antecedents.
Referring to a clear and specific antecedent is critical to maintaining clarity in writing. When a sentence uses a pronoun, the antecedent should be unmistakably identified to prevent any misunderstanding about what the pronoun is replacing. In the case of reflexive pronouns like 'himself', there is usually less confusion because they clearly reflect back on the noun immediately preceding them.