Answer:
D. It is caused by flowing negatively charged particles.
Explanation:
Current electricity is caused by flowing negatively charged particles. Current flows in a direction opposite the that of the charged particles.
The negatively charged particles can be electrons or ions in solutions.
As the electrons flows, current is generated in the opposite direction.
The potential difference is what drives the current and it is dependent on the available energy in the cell.
A constant velocity means the acceleration is zero.
To solve this problem we will begin by finding the pressure through density and average depth. Later we will find the Force, by means of the relation of the pressure and the area.

Here,
h = Depth average
= Density
Moreover,

Replacing,


Finally the force



Boyle's law states:
pV = C, where p = pressure, V = volume, C = constant.
Therefore,
p1V1 = p2V2
And the,
p2 = p1V1/V2
p1 = 512 kPa
V1 = 5l
p2 =?
V2 = 4l
Therefore,
p2= 512*5/4 = 640 kPa