How can a vector field be represented graphically?

One way to represent a vector field is through the concept of lines of force, which are lines tangent at every point to the direction of the field.
The density of the lines in a vector field is proportional to the intensity of the field.
When a field is conservative, the points where the lines converge are called sinks, and those where they emerge are called sources.
a) Only the first statement is correct.
b) Only the second statement is correct.
c) Only the third statement is correct.
d) All statements are correct.