Final answer:
The correct answer is 'them', which is the plural pronoun to refer to the fraternal Smith twins. The sentence should read: 'The Smith twins are fraternal, but many people cannot tell them apart.' Understanding pronoun usage is key to clarity in English.
Step-by-step explanation:
The question asks us to select the correct pronoun to complete the sentence: 'The Smith twins are fraternal, but many people cannot tell ____ apart.'
In this context, the correct pronoun to use is 'them', which is a plural pronoun that refers to more than one person. The sentence is describing the Smith twins as a pair, so the plural pronoun 'them' is appropriate. This makes the correct complete sentence: 'The Smith twins are fraternal, but many people cannot tell them apart.'
Understanding how to use personal pronouns correctly is essential for clear communication. It reflects the agreement between the pronoun and its antecedent in both number and gender. Since 'twins' is plural, 'them' is the must be correct option in the final answer.