What is the result？（）

A.2-1
B.2-4
C.2-5
D.3-1
E.3-4
F.3-5
G.Compilation fails.
H.An exception is thrown at runtime.

A.Compilation fails.
B.An exception is thrown at runtime.
C.The variable first is set to null.
D.The variable first is set to elements[0].

A.1
B.2
C.12
D.Compilation fails.
E.No output is produced.
F.An exception is thrown at runtime.