Correct Response: A. A changing magnetic field produces a changing electric field. This will occur regardless of the rate of change as long as it is nonzero. Answer choice B could only be correct if the changing magnetic field were cyclical. An electromagnetic wave would then be produced that matches the fundamental frequency of the changing magnetic field. The fundamental frequency is the first harmonic. However, it was not specified that the change of the magnetic field is cyclical, so this answer is incorrect. Answer choice C is possible, but only if the changing magnetic field has a frequency that falls within the range of the visible spectrum. Answer choice D is possible, but not necessarily true since an accelerating charge will also produce a changing magnetic field.
