Which statement about electric and magnetic fields is true.
1)electric and magnetic fields start at a positive and end at a negative.
2)magnetic fields must start at the north pole of a magnet and end at the south pole of the magnet.
3) electric fields must leave a positive charge and end on a negative charge.
4) electric fields and magnetic fields loop from north to south

Magnetic fields must start at the north pole of a magnet and end at the south pole of the magnet.

Explanation:

The lines that shows the direction of electric and magnetic field are called electric and magnetic field lines.The direction of electric field is from positive charge to negative charge.

The magnetic filed lines start at the north pole of a magnet and end at the south pole of the magnet.

Hence, the correct option is (2) "Magnetic fields must start at the north pole of a magnet and end at the south pole of the magnet".                                                        

More production

Explanation: Well, one thing scientist might want to change/ alter is the amount of tomatoes a plant makes. If they are able to do that farmers can produce more tomatoes with less space.