Answer
Answer: B is correct!
Work Step by Step
Three metal spheres are conductors, electric fields strength at all interior points is zero. When charged, all excess charges move to the surface.
For Voltage:
When they are wired together, think of them as a single entity. By definition, they have the same potential (or a single potential).
For electric field strength:
First, charges on the surface of a sphere can be seen as a single source charge at the center of that sphere (using Gaussian surface). By definition, the closer to the source charge the stronger the field strength. Sphere 1 has its surface closest to the center so the electric field strength on its surface must be the greatest, then sphere 2 and then 3.
