a web container question

[dx wu]

which is true about the web container request processing model?
A.The init method on a filter is called the first time a servlet mapped to that filter is invoked.
B.A filter defined for a servlet must alaways forward control to the next resource in the filter chain.
C.Filters associated with a named servlet are applied in the order they appear in the web application deployment descriptor file.
D.if the init method on a filter throws an UnavaibleException,then the container will make no furter attempt to execute it;

I think the answer is A and C, but there is only one answer .which?