A class games.cards.Poker is correctly defined in the jar file Poker.jar. A user wants to execute the main method of Poker on a UNIX system using the command：java games.cards. Poker What allows the user to do this？（）

A、put Poker.jar in directory /stuff/java， and set the CLASSPATH to include /stuff/java

B、put Poker.jar in directory /stuff/java， and set the CLASSPATH to include /stuff/java/*.jar

C、put Poker.jar in directory /stuff/java， and set the CLASSPATH to include /stuff/java/Poker.jar

D、put Poker.jar in directory /stuff/java/games/cards， and set the CLASSPATH to include /stuff/java