I assume this was multiple choice, so maybe next time put in those answers as well, it'll be easier on us.
But assuming you're referring to economics, inflation defines as: "A general increase in prices and fall in the purchasing value of money." Generally over a long period of time. Ex. A dollar was worth a lot more 100 years ago than it is now, and while our grandparents could buy a candy bar for maybe 5 or 10 cents when they were kids, now they go for around 1 - 1.5 dollars.