It is important to remember that commas are not merely pauses within a sentence, a mistake that is often made and which leads to writing issues. A comma is also a punctuation mark that is used to separate clauses, or ideas and that helps connect them without having to use periods all the time. Commas, according to rules, must be used in the following cases: before using coordinating conjunctions, such as but, and or for, after dependent clauses that begin a sentence, to separate series within a sentence, when you are going to use a clause that clarifies a word, or an idea before it, after introductory adverbs, such as Finally, before a quotation, when setting dates (day, month, year), when using the city-state combinations, after a freestanding word, like no, when you address something or someone directly in a text, between adjectives that modify a noun, among others. In this case, the correct answer is A, because the commas separate the main subject, Mother, the dependent clause in the middle, the main idea, which is that the subject works late and then in between the main idea and its dependent clause, which is that they eat supper at 8 because the mother works late.
