Marlena thought it looked warm outside, but it was freezing. The frigid, but sunny weather confused Marlena. The weather was sunny but, it was cold outside. Which sentence correctly uses a comma to create a compound sentence? Select the best answer.

Marlena thought it looked warm outside, but it was freezing.

Explanation:

The first sentence is a compound one! Two independent clauses are joined together with a comma and a coordinating conjunction.

The second sentence isn't a compound sentence, and the third uses a comma incorrectly.

Have a grand day!