1) Mixed economies are a mix of Command (regulated by the government) and free (Market) economy - the answer is b)
2)Today most countries have a mixed economy, there are few (such as North Korea) which have a command economy, but none have a true free market (for example drugs are regulated)
3)Inflation means that one needs more money to buy the same goods - this is measured by a rising Consumer Prize index (answer d)
4) this indicator would be a steady, but low inflation - but inflation is bad for the economy but lack of inflation is not really stable