As you are always drawing in your hands when you get a slice it is evident that the vertical swing has been delayed too long and is predominating as you are nearing your ball.
From experience I have found that those players who do not practically complete their downward sweep before they reach line b have trouble with slicing because the force being applied to bring the club head down to the ball in time is greater than that which is twisting the body around.
The consequence is that there is more force being applied vertically than horizontally, and they must pull in the hands to hit the ball at all. The majority of beginners start their vertical swing too quickly in order to get the club up over their heads, and this results in their predisposing their minds in favor of finishing the vertical part of the swing last. A sliced ball is inevitable under these circumstances.
There seems to be a peculiar construction of the mind which makes players return to the ball in the same way that they draw back from it, and if a step in the back swing is in its wrong order, that order will prevail on the downward swing. Any fault which is developed in the back swing is intensified on the downward swing because you are applying your maximum power at that time.
The clubs are built to give the ball the proper angle of rise when you are swinging parallel with the ground. What a very small percentage of players get off a fine, low ball when they hit it ! The majority seem to devote great care to getting their ball high in the air. In fact, I think that one of the commonest faults I see on the links is that of trying to get the ball up.
Habits are easily developed in golf and hard to break. Every one will occasionally get a ball off right, but it is the average that counts.
A great many of the experienced players will feel that they do not need to have their attention directed to this point, but if they were to get a strong sense of this fact they would be able to add very materially to their distance and accuracy.