Business cycles are best defined as fluctuation in aggregate economic activity in which : a. the decisions of businesses are the governing force behind the aggregate fluctuations-hence the term 'business cycles' b. many economic activities expand and contract together in a recurring-but not periodic-fashion c. industrial activities expand and contract in a recurring-but not periodic-manner d. all economic activities expand and contract in unison in a recurring and period fashion

Answer: b. many economic activities expand and contract together in a recurring-but not periodic-fashion

Explanation:

The Business Cycle refers indeed to fluctuations in the business cycle related closely with the rise and fall in production output of goods and services in an economy.

It come with stages being Expansion, Peak, Recession, Depression, Trough, and Recovery. What is most interesting is that the movers behind the business cycle are not a singular entity but rather a series of Economic activities that are interconnected and move together. This is why some activities herald stages in the Business Cycle while some follow it. But they all have a role to play.

It is also very important to note that this is NOT a periodic occurence because it doesn't happen per period and neither can it be predicted but it happens. It is Recurrent but not periodic in other words.