When an uncharged sphere of metal is placed inside a charged parallel plate capacitor, charges of opposite polarity are induced on the surface of the sphere.
Negative charge would be induced on the upper surface of the sphere and similarly positive charge would be induced on lower surface of the sphere. We know that, electric lines of force are always perpendicular to the surface and emerge from positive charge and enter into negative charge. Thus, the correct representation of the lines of force is given in the above figure.