Not an official problem (although some of the official "non-math DS" problems have had issues😨—they're definitely not all up to GMAC's usual meticulous standards).
This problem has a serious flaw: The central question ("How does inflation occur?") is ambiguous. We have no way of telling whether the problem writer meant to call
any valid mechanism for inflation "sufficient", or whether she/he meant to reserve "sufficient" for a
complete accounting of all possible causes of inflation.
We can rule out the latter possibility with decent confidence, though, because in that case we could not possibly hope to have any insight into the problem without extensive factual knowledge from economics—namely, we would have to
KNOW ALL possible causes of inflation. So, the question must have the former meaning:
If a statement EXPLAINS AT LEAST ONE cause/mechanism of inflation, then it's "sufficient"..
.
With the above realization in hand, statement 1 is clearly sufficient. Statement 2 contains the only other nontrivial step in the problem: we have to recognize that "an increase in prices" is the basic definition of inflation, making that statement also sufficient.
This step is probably the single thing here that's most reminiscent of how GMAC writes problems: Official DS problems often require
REPHRASING of the statements into equivalent forms that bear more directly on the central question.