When gravitational, magnetic and any forces other than static electric forces are not present, electric field lines in the space surrounding a charge distribution show

a. the directions of the forces that exist in space at all times.
b. only the directions in which static charges would accelerate when a points on those lines.
c. only the directions in which moving charges would accelerate when at points on those lines.
d. tangents to the directions in which either static or moving charges would accelerate when passing through points on those lines.
e. the paths static or moving charges would take.

A very useful way to graphically schematize a field is to draw lines that go in the same direction as that field at several points. This is done through the electric field lines, which are imaginary lines that describe, if any, changes in the direction of the electric field when passing from one point to another, so that these lines are tangent, in each point of the space where the electric field is defined, to the direction of the electric field at that point.

According to Newton's first law, the force acting on a particle produces a change in its velocity; therefore, the movement of a charged particle in a region will depend on the forces acting on it at each point in that region.

Therefore the electric field lines in space surrounding a charge distribution will show tangents to the directions in which either static or moving charges would accelerate when passing through points on those lines.

The correct answer is D.