When might cancellation of indebtedness result in a taxable event to a taxpayer$-$borrower?

When the borrower has been granted relief of the debt in bankruptcy

When the borrower is insolvent to a degree equal to or greater than the amount of the debt cancelled

When the borrower is insolvent, but to a degree lesser than the amount of the debt cancelled

When the borrower receives a discharge of student loans under the American Rescue Plan Act

All of the above could result in a taxable event to the taxpayer$-$borrower