If you make an electromagnet using a battery circuit and a steel nail, how can you increase its magnetic strength? Use a longer nail.

Wrap more coils of wire around the nail.

Replace the nail with a copper rod.

Remove the plastic insulation from the wire coil.
I would like a little help with this please,··

If i am correct it would be C

Explanation:

Electric energy travels better through copper than it does steel

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.