Answer and Explanation:
The explanation is as follows:
a. In the case when the unemployment reaches to the highest level and the results is in lowest so it would be due to trough
b. In the case when there is a decrease in unemployment and the production would be expand so this is due to an expansion
c. In the case when the economy is in full employment and the output would be generated in full capacity so this is due to peak
d. In the case when the real output is fallen for minimum two quarters so this is due to recession