为什么不选B

问题如下：

Q. When aggregate real personal income, industrial output, and the S&P 500 Index all increase in a given period, it is most accurate to conclude that a cyclical upturn is:

选项：

A.occurring. B.about to end. C.about to begin.

解释：

A is correct. Aggregate real personal income and industrial output are coincident indicators, whereas the S&P 500 is a leading indicator. An increase in aggregate personal income and industrial output signals that an expansion is occurring, whereas an increase in the S&P 500 signals that an expansion will occur or is expected to continue. Taken together, these statistics indicate that a cyclical upturn is occurring.