Which of the following could you do to increase the strength of an electromagnet? decrease the number of windings decrease the electric current change the core from wood to iron all of the above

I believe the most appropriate answer would be to change the core from wood to iron. This is because iron is a magnetic material while wood is not magnetic hence cant acquire magnetism. Other factors that would increase the strength of electromagnet would be; increasing the amount of electric current, and increasing the number of windings.