Milton Friedman argued that the economy is not in long-run equilibrium if the expected inflation rate the actual inflation rate.

 d.a and b

Explanation:

Inflation refers to the general rise in the price of goods and services in the economy and when stable can be considered good for the economy as it signifies that the country's economy is growing.

Milton Friedman argued that for an economy to be in long run equilibrium, the expected inflation rate must be equal to the actual inflation rate. If the expected rate is either lower or higher than the actual rate then the economy is not in equilibrium.

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