Which is true of magnetic field lines, but not electric field lines

a) they are not affected by their own source
b) they show which way iron shavings would align themselves
c) they re stronger near the source and get weaker farther away
d0 the closer the fields lines, the stronger the fields

B) they show which way iron shavings would align themselves

Explanation:

Let's analyze each statement:

A) they are not affected by their own source  --> this is true for both magnetic and electric fields. In fact, both fields are produced (and so affected) by a source (a magnet or a current in the magnetic field case, and an electric charge in the electric field case)

B) they show which way iron shavings would align themselves  --> this is only true for the magnetic field. In fact, the pieces of iron will align according to the magnetic field; however, since they are electrically neutral, they are not affected at all by an electric field.

C) they re stronger near the source and get weaker farther away   --> true for both magnetic and electric fields.

D) the closer the fields lines, the stronger the fields  --> also true for both magnetic and electric fields.

So, the correct answer is B.

explanation:

to push or pull an object in a certain direction is known as force. a force in moving an object from one place to another.

force depends on the mass of an object. so, more is the mass of an object more will be the force required to move the object.

thus, we can conclude that the use of force to move an object is push or pull.