Answer:
The AMT rates represent a progressive tax rate structure.
Explanation:
"AMT is designed to prevent taxpayers from escaping their fair share of tax liability through tax breaks. However, the structure was not indexed to inflation or tax cuts. This can cause bracket creep, a condition in which upper-middle-income taxpayers are subject to this tax instead of just the wealthy taxpayers for whom AMT was invented. In 2015, however, Congress passed a law indexing the AMT exemption amount to inflation."
Reference: Kagan, Julia. “Alternative Minimum Tax (AMT) Definition.” Investopedia, Investopedia, 10 Sept. 2019