Final answer:
The sentence that uses commas correctly is option B: Wen Yu, an old friend of the family, will be joining us for dinner.
Step-by-step explanation:
The sentence that uses commas correctly is option B: Wen Yu, an old friend of the family, will be joining us for dinner. Commas are used to set off the appositive phrase 'an old friend of the family'. The appositive phrase provides additional information about Wen Yu.
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