BJT propagation?

[etstudent]

I cannot find this anywhere in my books, I looked and looked, so any help will be appreciated.

In a noninverting buffer made with a bipolar junction transistor [BJT], propagation delay is longest when operation?

1 changes from saturation to cutoff
2 changes from cutoff to saturation
3 remains at zero
4 remain in saturation

My guess is is 3 but that is just a hunch. Any help would be great, hints, whatever, thanks.

[etstudent]

Thanks, I'm sure its in here, and I'm just overlooking it. Thanks again for the help.

[etstudent]

Found it. I just overlooked it several times, unlined it and still missed it. That is why you gotta go through these books several times. Thanks for the help.