. A business cycle is the a. period of time in which expansion and contraction of economic activity are equal. b. period of time in which there are three phases which are: peak, depression, and expansion. c. recurring growth and decline in real GDP. d. period of time in which a business is established and ceases operations

c. recurring growth and decline in real GDP.

Explanation:

A business cycle is also called a economic cycle or trade cycle, and it is the fluctuation of GDP up and down along its long term growth trend. A business cycle consists of a period of boom and contraction in sequence.

It shows rise and fall in production of goods and services within a country including output from businesses, individuals, households, nonprofits, and government.

There are 4 stages that make up the business cycle that is peak, recession , trough, and expansion.

there are so many examples for that in different areas, like biology experiment carried out in our lab recently.

here's one link :