Which interface must a class implement to be informed of a session creation event？（）

A. The session object must be declared explicity.
B. The request and response objects are available implicity.
C. The output stream is available through the implicit outStream object.
D. The servlet context is available through the implicit servletContext object.
E. The JspContext for the tag file is available through the implicit jspContext object.

A. pageContext.getAttribute（“foo”）；
B. getPageContext（）.getAttribute（“foo”）；
C. pageContext.getApplicationScope（“foo”）；
D. pageContext.getAttribute（“foo”，pageContext.APPLICATION_SCOPE）.getAttribute（“foo”）；
E. getPageContext（）.getScope（pageContext.APPLICATION_SCOPE）.getAttribute（“foo”）；

A. WAR files must be located in the web application library directory.
B. WAR files must contain the web application deployment descriptor.
C. WAR files must be created by using archive tools to designed specifically for that purpose. 
D. The web container must serve the content of any META-INF directory located in a WAR file.
E. The web container must allow access to resources in JARs in the web application library directory