NCAA Question

[dumbref]

I know the NCAA has a "fumble on 4ht down" rule but I am not sure how it applies to this situation.

A's ball 4th and 5, QB drops back to pass and is pressured. While scrambling toward the LOS he is hit behind the LOS and looses control off the ball:

A) and is caught by a running back 4 yards behind the end of the run and advances beyond the LTG.

B) and is recovered (grounded ball) by a running back 4 yards behind the end of the run and advances beyond the LTG.

I am pretty sure if the fumble goes foward, only the runner loosing the ball may recover & advance. And if another player recovers, it is returned to the end of the run. Correct? Does this apply to all fumbles in any direction on 4th down?