The use of commas in a series of three or more items is a common convention in Standard English. However, there are some cases where the comma before the conjunction "and" in a series is optional. The rule of thumb is that the comma is needed if omitting it would cause confusion or ambiguity. For example, in the sentence "The guests ate the main course, dessert, and coffee", the comma is not necessary because there is no risk of ambiguity without it. However, in the sentence "The guests ate the main course, dessert, and coffee, which was served in a fancy teacup", the comma is necessary to prevent the reader from misinterpreting "and coffee, which" as a phrase modifying "dessert." The comma is also necessary when the final item in the series is a long phrase or a clause. For example, in the sentence "The guests ate the main course, dessert, and a cup of coffee that was brewed especially for the occasion", the comma before "and" is needed because the final item in the series is a long phrase.
","stem_html":"Which of the following sentences correctly uses a comma before the conjunction "and" in a series?
","rationale_html":"The final item in the series is a clause, "which was chilled to perfection.", so the comma is needed to prevent the reader from misinterpreting "and a glass of wine, which" as a phrase modifying "dessert." The other choices do not have this issue because the final item in the series is not a long phrase or clause.
","correct_answer":["C"],"has_media":false,"has_mathml":false,"has_table":false,"source_created_at":null,"source_updated_at":null,"options":[{"label":"A","content_html":"The guests ate the main course, dessert, and the coffee was served with a dollop of whipped cream.
","ord":0},{"label":"B","content_html":"The guests ate the main course, dessert, and a special, extra-large cookie that was baked just for them.
","ord":1},{"label":"C","content_html":"The guests ate the main course, dessert, and a glass of wine, which was chilled to perfection.
","ord":2},{"label":"D","content_html":"The guests ate the main course, dessert, and coffee that was brewed with locally roasted beans.
","ord":3}],"attribution":{"source_id":"opensat","source_name":"OpenSAT community question bank","rights_holder":"OpenSAT contributors","canonical_url":"https://github.com/Anas099X/OpenSAT","retrieved_from":"https://pinesat.duckdns.org/api/questions","attribution":"Reading and Writing practice questions from the OpenSAT community question bank, whose licence permits free use of the database.","disclaimer":"OpenSAT items are community-written or AI-generated practice material, not official College Board questions; quality varies.","license":"OpenSAT LICENSE.md: the database may be used freely, including commercially, without restriction. Code is separately restricted.","redistributable":true,"item_count":1406}}