final answer:
Debt problems in Spain, Italy, and Greece arose from borrowing to finance the post-2008 financial crisis bailouts, leading to high deficits and austerity measures that questioned the euro's viability.
Step-by-step explanation:
The debt problems in countries such as Spain, Italy, and Greece were largely caused by the global financial crisis of 2008, which led these countries to borrow heavily to provide bailouts to their financial sectors. These borrowed funds significantly heightened their national deficits and, subsequently, these nations adopted austerity measures, including large decreases in government spending and significant tax increases. The associated economic strain triggered debates about the euro's viability, as severe austerity measures impacted economies and public welfare.