Which statement is true regarding the setting of the PCTFREE value for an index?

Which statement is true regarding the setting of the PCTFREE value for an index?

A.
It decides how much of a block to fill when the index is created.

B.
It has no role to play when segment space management is automatic.

C.
It keeps space reserved in a block for possible updates to existing rows in that block.

D.
It is the minimum percentage of a block that can be used for row data and overhead before new rows are added to the block.