Which of the following curves shown below can possibly represents electrostatic field lines?

Electrostatic field lines start or end only at 90° to the surface of the conductor. So curve (2) cannot represent electrostatic field lines. Electric field lines cannot form closed loops. So, curve (4) cannot represent electrostatic field lines. Also, electric field lines originate from positive and terminate at negative charge. So, curve (1) cannot represent electrostatic field lines. Only curve (3) represent electrostatic field lines.