Final answer:
The correct sentence is option B, which correctly uses commas to set off the appositive 'Starbucks' from the rest of the sentence.
Step-by-step explanation:
The correctly written sentence is: B. The world's largest chain of coffee stores, Starbucks, is opening a brand new store just around the corner. In this sentence, Starbucks is an appositive, which is a noun or noun phrase that renames or clarifies another noun next to it. Appositives should be set off by commas when they provide non-essential information. In this case, the name Starbucks specifies which coffee chain, but is not essential to the meaning of the sentence. Hence, it requires commas before and after the name.