这个题目怎么去判断独立性更强呢？

NO.PZ2015120604000154问题如下Whiof the following situation is least appropriate for using the pairecomparisons test? All the populations are supposeto normally stributeA.Anastasia wants to test whether meannureturns over the last forty years are equfor can company's stoanoil company's bon She assumes the both returns have equvariances.B.Blanche Brown wants to test if the memonthly returns over the last three years are equfor airline's stoanmeccompany's stock. She assumes the both returns are with equvariances.C.Lauren Lee wants to test if the memonthly returns over the last five years are equfor a beer company's stoanoil company's stock. He assumes the both returns are with equvariances.A is correct.The returns of bonanstoare relatively inpennt. The pairecomparisons test requires samples are not inpennt. Storeturns are all relateto market returns, so the samples of B anC are both likely pennt.beer和oil，airline 和mecal知道怎么会有联系哦？

NO.PZ2015120604000154问题如下Whiof the following situation is least appropriate for using the pairecomparisons test? All the populations are supposeto normally stributeA.Anastasia wants to test whether meannureturns over the last forty years are equfor can company's stoanoil company's bon She assumes the both returns have equvariances.B.Blanche Brown wants to test if the memonthly returns over the last three years are equfor airline's stoanmeccompany's stock. She assumes the both returns are with equvariances.C.Lauren Lee wants to test if the memonthly returns over the last five years are equfor a beer company's stoanoil company's stock. He assumes the both returns are with equvariances.A is correct.The returns of bonanstoare relatively inpennt. The pairecomparisons test requires samples are not inpennt. Storeturns are all relateto market returns, so the samples of B anC are both likely pennt.oil和mecal公司的股票为什么有关系哦？

NO.PZ2015120604000154问题如下Whiof the following situation is least appropriate for using the pairecomparisons test? All the populations are supposeto normally stributeA.Anastasia wants to test whether meannureturns over the last forty years are equfor can company's stoanoil company's bon She assumes the both returns have equvariances.B.Blanche Brown wants to test if the memonthly returns over the last three years are equfor airline's stoanmeccompany's stock. She assumes the both returns are with equvariances.C.Lauren Lee wants to test if the memonthly returns over the last five years are equfor a beer company's stoanoil company's stock. He assumes the both returns are with equvariances.A is correct.The returns of bonanstoare relatively inpennt. The pairecomparisons test requires samples are not inpennt. Storeturns are all relateto market returns, so the samples of B anC are both likely pennt.这个感觉考的是，是否独立的前提。可是BC就说明不独立了吗？

NO.PZ2015120604000154问题如下Whiof the following situation is least appropriate for using the pairecomparisons test? All the populations are supposeto normally stributeA.Anastasia wants to test whether meannureturns over the last forty years are equfor can company's stoanoil company's bon She assumes the both returns have equvariances.B.Blanche Brown wants to test if the memonthly returns over the last three years are equfor airline's stoanmeccompany's stock. She assumes the both returns are with equvariances.C.Lauren Lee wants to test if the memonthly returns over the last five years are equfor a beer company's stoanoil company's stock. He assumes the both returns are with equvariances.A is correct.The returns of bonanstoare relatively inpennt. The pairecomparisons test requires samples are not inpennt. Storeturns are all relateto market returns, so the samples of B anC are both likely pennt.请老师帮忙分析一下三个里面的商品的两两独立性呢？