问题如下：
Which of the following groups best illustrates a population?
选项：
A.The 500 companies in the S&P 500 Index
The NYSE-listed stocks in the Dow Jones Industrial Average
The Lehman Aggregate Bond Index as a representation of the US bond market
解释：
A is correct. A population is defined as all members of a specified group. The S&P 500 Index consists of 500 companies, so this group is the population of companies in the index.
B is incorrect because there are several Dow Jones component stocks that are not traded on the NYSE, making the NYSE group a subset of the total population of stocks included in the Dow Jones average.
C is incorrect because although the Lehman Aggregate Bond Index is representative of the US bond market, it is a sampling of bonds in that market and not the entire population of bonds in that market.
想问一下，这个考核的考点是什么？
