The stamp act was a tax on all of the following except

a. postage stamps.
b. playing cards.
c. newspapers.
d. pamphlets.

I believe it is A. American colonists were required to pay a tax on every piece of printed paper including playing cards, legal documents, newspapers and other publications. The reason it is called the Stamp Act is because all of these papers had to be physically stamped to prove that they had paid the tax. So it has nothing to do with taxing postage stamps, so the answer should be A.