Passage Summary: An economist explains that price changes happen when money and production get out of sync. Because their country has a very steady money supply, they believe the economy will stay stable.

Conclusion: The economist's country is unlikely to suffer from significant inflation or deflation.

Reasoning: Inflation and deflation are caused by an imbalance between the money supply and the production of goods; since the country's money supply is anchored by gold and remains stable, these imbalances are unlikely to occur.

Analysis: To find the necessary assumption, we need to look for a hole in the economist's logic. They have established that the money supply is stable, but their own definition of inflation/deflation depends on the *relationship* between money and production. If the money supply stays still but the production of goods and services fluctuates wildly, you would still get inflation or deflation. Therefore, the argument relies on the assumption that production in this country will not grow or shrink significantly enough to cause an imbalance. Look for an answer that addresses the stability of production.