A student is creating a table with properties of electromagnetic and mechanical waves.

The property of the wave marked X is related to the source of the wave

Explanation:

The source of of origin of waves

Electromagnetic wave are waves that consists of varying electric and magnetic field that vibrate perpendicular to each other and to the direction of propagation of the wave and they are therefore transverse waves and transfer energy

Electromagnetic waves originate from the vibration of charged particles that gives off varying electric and magnetic fields

Mechanical waves are defined as waves that require a material medium such as air, water, metal, plastic, stretched leather, or wood to propagate

Mechanical waves originate from vibration of the particles of a medium

Sound waves which is a form of longitudinal mechanical waves that propagates by the vibration of the particles of a given medium about a point parallel to the direction of propagation of the wave.

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.