Regarding the AMT tax, which statement is correct?

$($I$)$ The AMT exemption is phased out by $50\%$ for each dollar over a threshold amount

$($II$)$ The AMT liability is the amount that exceeds the regular tax liability

A$.$

$($I$)$ Only

B$.$

$($II$)$ Only

C$.$

Both statements $($I$)$ and $($II$)$

D$.$

Neither statement $($I$)$ or $($II$)$