The central argument of the American colonists against the Stamp Act that is not understood by the writer is:
C. that it is not the amount of tax that is the problem but rather the fact that the colonists were not involved in passing the tax.
The excerpt indicates a lack of understanding of the colonists’ primary grievance, which was not solely the financial burden of the tax but rather the principle of taxation without representation. The writer dismisses the taxes as minor, missing the larger issue of the colonists' lack of say in the legislation that affected them.