In which of the following situations is the greatest amount of work accomplished?

a boy lifts a 2-newton box 0.6 meters.
a boy lifts a 4-newton box 0.6 meters.
a boy lifts a 6-newton box 0.3 meters.
a boy lifts a 9-newton box 0.3 meters.

work = force x distances

A - moving 2 newton's up 0.6 meter = 1.2 joules
B - moving 4 newton's up 0.6 meter = 2.4 joules
C - moving 6 newton's up 0.3 meter = 1.8 joules
D - moving 9 newton's up 0.3 meter = 2.7 joules
The greatest amount of work is in example D. 

 D is your answer.

the electrical  conductivity  of asolution  of an electrolyte is measured by determining the resistance of thesolution  between two flat or cylindrical electrodes separated by a fixed distance.

gold is my favorite solid.