Concept:A business cycle is the periodic rise and fall of economic activity around a long-term trend.
Explanation:A business cycle involves alternating phases of expansion and contraction.
The contraction phase is commonly called a recession.
During a recession, output, income, and employment decline.
Thus, recession is directly associated with the business cycle.
Unemployment, inflation, and seasonal variation are related economic issues, but they are not the defining feature of the business cycle itself.
Answer:A. Recession