An Inferior Product with a Large Advertising Budget Sells Well

Multiple Choice

An inferior product with a large advertising budget sells well when it is introduced, but sales fall as people discontinue use of the product. Suppose that the weekly sales S are given by where S is in millions of dollars and t is in weeks. After how many weeks will sales be maximized? ​

A) two weeks
B) one week
C) ​three weeks
D) ​four weeks
E) ​five weeks