The correct answer is C. All the three flavors—chocolate, vanilla, and strawberry—were sold out at the ice cream store
Explanation:
Elongated hyphen, also called em dash is a punctuation mark (—) which is longer than the dash and the en dash, mainly used to replace parenthesis, commas or even colons; in most cases em dashes introduce extra information that clarifies some section of the sentence but is not necessary for the sentence to be complete, in this case, em dashes are used in the middle of the sentence and the extra information is placed between the em dashes without spaces. Also, em dashes are used to emphasize the end of the sentence and in this case, only one em dash is required. Considering this, the sentences that correctly uses elongated dashes or em dashes is "All the three flavors—chocolate, vanilla, and strawberry—were sold out at the ice cream store", because in this sentence the em dashes are used to introduce extra information that clarifies the three flavors, but that is not necessary to understand the sentence, which means they replace commas or parenthesis and therefore are correctly used.
