Two conducting spheres of radii $20\, cm$ and $15\, cm$ are placed on insulating stands. Both are given an equal charge of $10\ \mu C$. When they are connected by a copper wire and then disconnected,which of the following is true?

• A
  Both spheres will have the same charge.
• B
  The surface charge density will be higher on the sphere of radius $20\, cm$.
• C
  The surface charge density will be lower on the sphere of radius $20\, cm$.
• D
  The surface charge density will be the same on both spheres.