Which sentence correctly uses a comma before a coordinating conjunction joining two independent clauses?

Which sentence correctly uses a comma before a coordinating conjunction joining two independent clauses?

• A. She went to the store, and she bought milk.
• B. She went to the store and, she bought milk.
• C. She went to the store, but bought milk.
• D. She went to the store but bought milk.

Answer: (A)

A comma before a coordinating conjunction is used when joining two independent clauses. Each side can stand alone as a sentence, and the comma helps signal that two complete thoughts are being linked. In the sentence with the comma before “and,” you have two complete thoughts: “She went to the store” and “she bought milk.” They’re neatly connected by and, with a comma signaling the pause between them. That matches the standard rule. The other options misplace punctuation or structure. A comma after the conjunction disrupts the flow between two independent clauses. Leaving out the subject after the conjunction leaves the second part incomplete, so it isn’t two independent clauses. And omitting the comma before the conjunction when two independent clauses are joined isn’t following the usual convention, unless the clauses are extremely short and tightly related, which this sentence doesn’t require in standard practice.

A comma before a coordinating conjunction is used when joining two independent clauses. Each side can stand alone as a sentence, and the comma helps signal that two complete thoughts are being linked.

In the sentence with the comma before “and,” you have two complete thoughts: “She went to the store” and “she bought milk.” They’re neatly connected by and, with a comma signaling the pause between them. That matches the standard rule.

The other options misplace punctuation or structure. A comma after the conjunction disrupts the flow between two independent clauses. Leaving out the subject after the conjunction leaves the second part incomplete, so it isn’t two independent clauses. And omitting the comma before the conjunction when two independent clauses are joined isn’t following the usual convention, unless the clauses are extremely short and tightly related, which this sentence doesn’t require in standard practice.