Which three are guaranteed to be valid for the  element of a web application deployment descriptor？（）

A. ${vals.2 }
B. ${vals ["2"]}
C. ${vals.index }
D. ${vals[index]}
E. ${vals} [index]
F. ${vals.（vals.index）}
G. ${vals[vals[index-1]]}

A. Error
B. Exception
C. Throwable
D. Request error
E. Request exception

A. The function method must have the signaturepublic： String spin（）.
B. The method must be mapped to the logical name “spin” in the web.xml file.
C. The function method must have the signature：public String spinIt（）.
D. The function method must have the signature：public static String spin（）.
E. The function method must have the signature：public static String spinIT（）.
F. The function class must be named Spinner， and must be in the package com.example.