The correct option is A children -
According to general rule, the em dash is often used to resume a scattered subject in a sentence. Thus, the correct answer in the given sentence must be Option A.
Option B is incorrect. A comma is used to indicate a pause in a sentence.
Option C is incorrect. A colon is used to introduce a list of items in a sentence.
Option D is incorrect. A semi colon is used to connect two independent clauses in a sentence.