I believe the answer is the 3rd one
The root word bi means two.
One example of this root word being used is the word bicycle.
The root word is used so as to tell people that this bicycle has two wheels.
A unicycle is a riding device that has one wheel.
To restate the central point of the argument and make a final bid for the audience's support.
That was the answer for Apex, if you're not using this for apex, I still hope I helped somewhat.
'Transient' is the correct vocabulary word.
