Final answer:
The capacitance of the two conducting spheres far apart is not represented by a combination of both radii as in the options provided, so the correct answer would be E. none of these.
Step-by-step explanation:
The two conducting spheres with radii R1 and R2, where R1 is greater than R2, have their capacitance determined by the geometry of the spheres. Since these spheres are far apart and can be considered isolated, each will have a capacitance proportional to its radius, not a combination of both radii. In the case of an isolated spherical conductor, the capacitance (C) is directly proportional to its radius (R). Therefore, the correct answer to the relationship that represents the capacitance of the two isolated spheres is not found in the options provided, since each sphere's capacitance is individually proportional to its own radius, not a function of both radii combined. Hence, the correct choice is E. none of these.