我朋友今天考PA，遇到一多选题

For UNDO tablespace, which of the following statement are ture?

1.Storage parameters of all undo segments should be equal.
2.The undo tablespace MUST be a dictionary managed tablespace.
3.To avoid a table overflow, the UNDO tablespace can be set to be autoextensible.
4.Transformation of rollback to undo tablespace can be performed with BRspace in one-step procedure.
5.Undo segments are overwritten first after undo retention time.

我给的答案是 1，3，希望没帮倒忙~