The architect considers many aspects when he designs a house. if one had to name just one aspect that would sum up all these considerations, it would be economy flexibility livability house size

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.