Inflation is the

general rise in prices over time
general reduction of prices over time
decline phase of the business cycle
decline in costs for a specific industry

Inflation is the general rise in prices over time.

Explanation:

In economics, inflation means a decline in the purchasing power of money and the resulting rise in prices, therefore the decline in the real value of money. It can also be defined as a general rise in prices to weaken the purchasing power of money.  

Inflation decreases the purchasing power of money, so that the same amount of money can no longer buy the same amount of products, services or labor, and monetary savings lose their value. On the other hand, the nominal value of real assets, such as real estate, is increasing. The opposite of inflation is deflation, that is, falling prices.

associative property of addition