A.Compilation fails.
B.An exception is thrown at runtime.
C.Synchronizing the run（） method would make the class thread-safe.
D.The data in variable "x" are protected from concurrent access problems.
E.Declaring the doThings（） method as static would make the class thread-safe.
F.Wrapping the statements within doThings（） in a synchronized（new Object（））{} block would make the class thread-safe.