Final answer:
(1) p, r, and s only. Software is re-engineered to adapt to changing requirements, improve maintainability, and change functionality and architecture;
Step-by-step explanation:
The correct answer is option (1) p, r, and s only. Re-engineering software is a complex process undertaken to ensure that legacy systems can adapt to changing requirements, which may include market and business environment changes.
Another significant reason is to improve software maintainability; this relates to comprehending, repairing, meeting new requirements, preventing system failures, and ensuring satisfactory performance.
Finally, re-engineering allows for a change in the functionality and architecture of the software, which can result from strategic business decisions or a need to incorporate better structures because of evolved business logic or practices.
Upgrading to newer technology or paradigm, which is option q, is usually part of a broader scope termed software modernization, rather than the narrower focus of re-engineering which doesn't necessarily include shifting paradigms or technologies but may do so if it aligns with the other goals.