garbage collection's doubt

[Rubel Ahammad]

MindQ's

Which of the following statements about Java's garbage collection are true?

a) The garbage collector can be invoked explicitly using a Runtime object.
b) The finalize method is always called before an object is garbage collected.
c) Any class that includes a finalize method should invoke its superclass' finalize method.
d) Garbage collection behavior is very predictable.

ans given: a,b,c.

But,
a: we only can request garbage collector using Runtime Object.
b: K&B says that , you can't count on the garbage collector to ever delete an object. So Any Code that you put into your class's overriden finalize() method is not guaranteed to run.

I think only correct answer is c.
coz:
Kalid Mugal's SCJP1.2 Says(Page 253) "Finalizers are not implicitly chained like constructors for subclasses, therefore a finalizer in a subclass should explicitly call the finalizer in its superclass as its last action.

[Arvind Giri]

.
Dear Rubel,
The 2nd option can be taken in other words as "before an object is garbage collected, the finalize method is always called". now it seems ok.

and about 1st option he is saying only abt invoking. which doesn't mean sure excution. explicitly invoking is like making request.

[Surasak Leenapongpanit]

Option a) can be called by System.gc() or Runtime.gc().