All energy transformations end in this form of energy because of their inability to be 100% efficient,
1. chemical
2. thermal
3. mechanical
4. electricity

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.