The following five sentences, labeled 1 to 5, relate to a single topic. Four of these sentences can be arranged to form a logical paragraph. Identify the sentence that does not fit with the others and enter its number as your answer.

1. Inflation targeting, though widely adopted for its perceived clarity in achieving price stability, encounters profound operational complexities derived from the intricate interplay of economic fundamentals and policy lags.
2. A significant challenge arises when central banks grapple with persistent supply-side shocks that elevate price levels irrespective of demand conditions, often compelling a difficult choice between growth and inflation containment.
3. The efficacy of modern inflation-targeting regimes, particularly their reliance on anchored inflation expectations, can be severely tested by periods of heightened geopolitical risk or structural transformations in global supply chains.
4. Consequently, the successful navigation of price stability goals under such frameworks frequently necessitates a more nuanced approach than initially conceptualized, demanding adaptive strategies beyond merely managing aggregate demand.
5. The global proliferation of explicit inflation targeting in the late 20th century primarily stemmed from the perceived failures of monetarist experiments and exchange rate pegs in managing chronic inflation.