Answer:
Rectangular path
Solution:
As per the question:
Length, a = 4 km
Height, h = 2 km
In order to minimize the cost let us denote the side of the square bottom be 'a'
Thus the area of the bottom of the square, A = 
Let the height of the bin be 'h'
Therefore the total area, 
The cost is:
C = 2sh
Volume of the box, V =
(1)
Total cost,
(2)
From eqn (1):

Using the above value in eqn (1):


Differentiating the above eqn w.r.t 'a':

For the required solution equating the above eqn to zero:


a = 4
Also

The path in order to minimize the cost must be a rectangle.
'Pressure' is (force) / (area).
The only choice with those units is #1 .
This topic is actually quite controversial, but the answer in this case would be C.
Just some food for thought, the 2nd law of thermodynamics entropy of the universe is always increasing, but that doesn't necessarily mean that earth's entropy has to. As long as the net change in entropy of the universe is increasing it doesn't matter if one planet is decreasing a nominal amount. Next, Earth as said is not a closed system and you could argue that the sunlight and energy from the sun is increasing the total energy within the system that is earth meaning that it is increasing in entropy. Next, if you consider increasing entropy as an increase in the number of possible permutations that the universe or parts of the universe can take, then it is completely possible that an ordered planet and life is possible, although rare. This theory explains why there are so many life forms and why entropy is actually increasing when divergent evolution occurs.