a problem about data block

this is problem about data block at real oracle 8i ocp exam.
i don't sure the right answer, please explain
Which two prameter might affect the concurrency of transactions on a data block? (choose two)
A.PCTUSED
B.PCTFREE
C.INITRANS
D.MAX_EXTENTS
E.NEXT_EXTENTS
i choose : B,C
i put the problem at ocp furmus, but no one answer, hope have answer at here.

Hi,
Your answer is exactly correct. The lock contention is depends on INITRANS & PCTFREE .
The first is no of transactions can update that datablock simultaneously is depends on INITRANS.
The second one is if u set INITRANS to more than 1, it allows two TX's can update on that datablock. then the contention is switched to the available space, to update the row(s). If u have not enough space to update the row(s), it causes the TX to wait. The space available for update is defined by PCTFREE.
Other parameters are not related.

your answer is right...............you can refer oracle 24X7 tips and techniques for the explanation..........................

regards
hrishy

thank you very much for vutukuri and hrishy