单选题In form-based authentication， what must be included in the HTML returned from the URL specified by the element？（）Aa base-64 encoded user name and passwordBa form that POSTs to the j_security_check URLCan applet that requests the user name and password
题目
单选题
In form-based authentication， what must be included in the HTML returned from the URL specified by the element？（）
A
a base-64 encoded user name and password
B
a form that POSTs to the j_security_check URL
C
an applet that requests the user name and password from the user
D
a hidden field that supplies the login-constraint used by the application