Final answer:
The true statement is that certain states have no state income tax. States have different tax structures, with some using a flat rate or graduated rate, and a few having no state income tax at all, resorting to other forms of taxation to generate revenue.
Step-by-step explanation:
Among the statements provided, a. Certain states have no state income tax is the true statement. In the United States, different states have different tax structures. While most states impose a state income tax, there are exceptions such as Alaska, Florida, Nevada, South Dakota, Texas, Washington, and Wyoming, which do not have individual state income taxes. However, these states usually raise the needed revenue through other means, such as higher property taxes or sales taxes. Additionally, it's worth noting that not all states that do have a state income tax use a flat tax rate; some have a graduated rate similar to the federal income tax structure.