In Constructing the CPI,the BLS Has to Deal with Commodity

In constructing the CPI,the BLS has to deal with commodity substitution bias,which is defined as

A) consumers' substitution of discount stores for full service stores to avoid the higher prices in the full service stores.
B) consumers' substitution of cheaper goods for goods whose prices increase.
C) the bias from quality changes in existing products that cause prices to increase.
D) the bias from new goods being introduced that are more expensive than older goods.
E) the bias that arises because the BLS changes the CPI market basket each month.