Given an HttpServletRequest request and an HttpServletResponse response：
41.HttpSession session = null；
42.// insert code here
43.if（session == null） {
44.// do something if session does not exist
45.} else {
46.// do something if session exists47. }
To implement the design intent，which statement must be inserted at line 42？（）

A.It can be invoked only from the doGet or doPost methods.
B.It can be used independently of the getRemoteUser method.
C.Can return "true" even when its argument is NOT defined as a valid role name in the deployment descriptor.
D.Using the isUserInRole method overrides any declarative authentication related to the method in which it is invoked.

A.<realm-name>
B.<url-pattern>
C.<description>
D.<web-resource-name>
E.<transport-guarantee>

A.<realm-name>
B.<auth-method>
C.<security-role>
D.<transport-guarantee>
E.<web-resource-collection>