What do electric field lines indicate?

Electric field lines are a visual representation of the electric field around charged objects. They illustrate both the direction and strength of the electric field in a given region. When considering the direction of the electric field vector, these lines point away from positive charges and towards negative charges. Hence, the correct option emphasizes the primary role of electric field lines in showing the direction in which a positive test charge would be pushed if placed in the field.

While electric field lines do provide insight into the strength of the electric field and how tightly they are packed indicates the field's strength (closely packed lines correspond to stronger fields), the primary utility of the lines is in indicating direction. The other choices relate to different aspects: the interaction between electric and magnetic fields pertains to electromagnetic principles, while distance between charged objects does not directly correlate with the electric field lines themselves.