Violation in (a), because the ball was touched twice by A1’s hand(s) during a dribble, before it touched the floor.
In (b), even though the dribble was interrupted it has not ended and A1 may continue the dribble.
In (c), the dribble ended when A1 caught the ball; and it ended in when it was fumbled.
Even though the dribble has ended in (c) and (d), A1 may recover the ball but may not dribble again.