Answer: b) TRUE and d) TRUE
Explanation: a) FALSE the electric field lines are used to represent the charges postives and negatives.
b) TRUE it is the definition of electric field lines , they are tangent to the electric field vector.
c) FALSE the electric field lines only for conductor are perpendicular to the surface in other any situation there is a tangencial electric field components.
d) TRUE since it is a way to describe and imagine the effect of vectorial fields.
e) FALSE