These type of general rulings, as most IRS released commentary, don't get into detail on complicated situations. As noted in my comment 4, debt (recourse or non-recourse) add another level of complexity.
This area is handled in Section 752 of the code and regulations and the interaction with Section 731.
As noted previously, debt is included in basis (not capital account) and a relief of debt is treated the same as if cash was distributed; reduces basis.
As a result, you need to understand the mechanics, mostly the seller, and the impact on basis and the ultimate gain or loss on sale.
To respond to your specific questions, both a and b could result in a tax implication where income is recognized. The key is to minimize that impact or at least understand the impact so it is not a surprise.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
