多选题 Given that the root directory contains a subdirectory called "office" that contains some files for a Java application, if "X" and "Y" are unknown arguments, and the following command is invoked from the root directory in order to create a JAR file containing the office directory:
jar -cf X Y
Which are true? (Choose all that apply.)

A、 "X" should be the file name of the JAR file, and "Y" should be "office".
B、 "X" should be "office", and "Y" should be the file name of the JAR file.
C、 Specifying a file name of the JAR file here is optional.
D、 Ifa file name is not specified here, a file named office.jar will be created.
E、 The file name, if specified, must be ended with .jar extension.
F、 It is required that the "office" directory must initially have a subdirectory called "META-INF".
G、 All of the files other than .java and .class files must be initially placed in the META-INF directory.

【正确答案】 A

【答案解析】