Final answer:
Equipotential lines are used to represent the electric potential in the electric field.
Step-by-step explanation:
Equipotential lines are used to represent the electric potential (option 2) in the electric field. They are lines that connect points with equal electric potential. These lines are always perpendicular to the electric field lines. Equipotential lines provide a visual representation of how the electric potential varies in different regions of the electric field.