Explanation :
It is given that,
Area of the container,

Load carried by piston, m = 350 kg
Pressure on the upper surface of the liquid is defined as the force acting per unit area.
Mathematically it can be written as :

From Newton's second law of motion :
F = m a
So,


P = 3430 Pa ( Pa = pascal)
or
P = 3.43 kPa
So, the correct option is (D)
Hence, this is the required solution.