The term "business fluctuations" refers to:
a) the different stages of a product cycle.
b) changes in the prices of goods and services over time.
c) movement in real gdp around its long-term trend.
d) the trend in real gdp over a long period of time.

c) movement in real GDP around its long-term trend.

Explanation: Business fluctuation is defined as the variation or movement that occurs in the GDP (Gross Domestic Product) ,i.e. increment or decrement of GDP .

The increment and decrement occurs in the form of movement of GDP over a long duration. Business fluctuations occurs due to capital availability, supply and demand etc.

Other options are incorrect because product levels and price change does not generate business fluctuations. Overall movement of GDP is depicted from GDP's trend .

Thus , the correct option is option(c).