Which switches must be pressed to make bulb X come on? 1 and 2 only
1 and 3 only
2 and 3 only
All three of them

the answer for apex is the lowest

it was given as a lesson and guide for prayer.

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.