Which of the following sentences uses commas correctly?

Question 6 options:

Josephine worked late on Friday but she still got up early Saturday morning.

Josephine worked late on Friday, but she still got up early Saturday morning.

Josephine worked late on Friday, but she still, got up early Saturday morning.

Josephine, worked late on Friday, but she still got up early Saturday morning.

Commas are a punctuation mark that are used for two things; divide words in a set and also, set a pause within a sentence when no period is being used. There are several cases in which you use a comma. Some of these are: when using coordinating conjunctions, like and, for, but, etc. After a dependent clause that starts a sentence, to separate items in a sentence, after introduction adverbs like However, when you are going to use quotations and also when after using information like dates or city-states, among others.

In this particular case, we have two clauses. One where the subject, Josephine, is mentioned, and the second clause, which is preceded by a connecting conjunction, which is but. Given the rules mentioned before, since these two clauses are joined by the word "but", the comma must precede the coordinating conjunction. This is why the correct answer is B.