Final answer:
Monetary policy was tighter in the 1981-1985 period compared to the preceding period, indicating higher real and nominal interest rates. The nominal interest rate generally decreases in periods of lower inflation. Therefore, the correct option is B and C.
Step-by-step explanation:
In the 1970s, Australia experienced high inflation rates, which prompted a tight monetary policy by the Federal Reserve. The real interest rates were negative during this period, indicating loose monetary policy. However, in the 1981-1985 period, the real interest rate was higher than in the preceding period, showing a tighter monetary policy. So, option B is correct.
In the periods of lower inflation, the nominal interest rate was generally lower. This is because lower inflation reduces the need for high interest rates to combat inflation. Therefore, option C is also correct.
Based on the information provided, option A is incorrect as monetary policy was tighter in the period following the peak of inflation.
Therefore, the correct statements are B and C.