Their items could be delivered quickly and efficiently. The railroads could also be all over the area and the train could travel from one place or another and deliver the necessary items to those companies.
The correct answer among the choices given is option A. For a fusion reaction to happen, matter needs to be in the plasma state. For fusion reaction to happen special conditions should be met to overcome the energy required. One is that the temperature should be high to give atoms enough energy to overcome any resistances. It requires about 100 million Kelvin of temperature. At this point, hydrogen occurs as a plasma.
