In the given examples, the one that contains a subordinating conjunction is:
A. Charlotte swept the floor after she finished cooking.
Explanation:
1. A subordinating conjunction is a word that connects a subordinate (dependent) clause to a main (independent) clause.
2. In this example, "after" is the subordinating conjunction that introduces the dependent clause "she finished cooking," which cannot stand alone as a complete sentence.
3. The main clause is "Charlotte swept the floor," which can stand alone as a complete sentence.
4. Therefore, option A is the correct choice containing a subordinating conjunction.