Answer: 0.98kJ/kg
Explanation: for a kilogram mass of this system, raising the system at a height h gives it a potential energy of the magnitude gh,
Where g is gravitational acceleration,
and h is the height difference.
This system will have an energy change of
PE = 100*9.8 = 980 J/kg
This becomes 980/1000 kJ/kg
= 0.98kJ/kg