Identify the following items as an AMT adjustment to taxable income (A), a tax preference item (P), or neither (N):
a. Percentage depletion in excess of a property's adjusted basis at the end of the tax year.
b. The Sec. 179 expense and first-year MACRS depreciation claimed on a machine costing $200,000 and placed in service in the current year.
c. The difference between gain on the sale of the asset in Part b for taxable income purposes and alternative minimum taxable income purposes.
d. Tax-exempt interest earned on State of Michigan private activity bonds.
e. Tax-exempt interest earned on State of Michigan general revenue bonds.
f. 75% of the excess of adjusted current earnings (ACE) over pre-adjustment AMTI.