For a system of concentric conducting spheres of radii a and b (b > a), select the correct statements.

Select all that apply

• Option A

  C = 4πε₀ab/(b-a) when the outer sphere is earthed.

• Option B

  U = [Q²/(8πε₀)](1/a - 1/b) for the arrangement in (A).

• Option C

  If the inner sphere is earthed, equal and opposite charges are held by the conductors.

• Option D

  None of these