An electromagnetic field exists only when there is

ANS:D - current

In most conductors, the magnetic field exists only as long as the current is flowing (i.e. An electrical charge is in motion).

An electromagnetic field is a property of space caused by the motion of an electric charge. A stationary charge will produce only an electric field in the surrounding space. If the charge is moving, a magnetic field is also produced. An electric field can be produced also by a changing magnetic field.