Please help me
the formula is E = P x t

The battery doesn't 'use' power.  The battery produces the power that all the other electrical devices use.

If the starter motor is using 2,520 watts, then the battery is producing energy at the rate of 2,520 watts.  That means 2,520 Joules of energy every second.

Thanks for giving us the formula.

E = P x t

Energy = Power x Time

Energy = (2,520 watts) x (1 second)

Energy = 2,520 Joules  

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.