Use of the undo tablespace as opposed to the backup segment has a few benefits. Do you have proof for your assertion?

I've created a BST inserting keys 18, 56, 28, 40, 35, 38, 36, 20, and 24 in that order into an inititally empty BST. Now, I'm being asked to delete key 28 and I'm stuck between what I think are two options. I've added an image below for reference. Any help with this is appreciated!  **Please do not use Chegg or other comparable resources as they do not provide an explanation of how to get to the answer**

Undo statistics are used to fine-tune the undo tablespace. Do undo tablespaces provide any useful information? Who has access to the undo tablespace's statistics and may examine them? There are strict rules in Oracle 11g.

Which of the two options, a low or high reuse factor, is better for frequent reuse patterns? Why don't you just provide an example?