The introductory clause is placed at the beginning of a sentence.
The correct answer is "at the beginning" of a sentence. An introductory clause is a dependent clause that provides additional information or context to the main clause of the sentence. It usually comes before the main clause and helps to set the stage for the rest of the sentence. Keep in mind that sometimes a comma is used after the introductory clause, especially if the introductory clause is longer or if there is a clear pause between the introductory clause and the main clause.