A decrease in photon energy results in which of the following?

A decrease in photon energy is fundamentally related to the properties of electromagnetic radiation, which includes X-rays and other forms of light. According to the principles of physics, the energy of a photon is directly proportional to its frequency and inversely proportional to its wavelength.

When the energy of a photon decreases, the frequency must also decrease in order to maintain the relationship articulated by the equation (E = h \cdot f), where (E) is energy, (h) is Planck's constant, and (f) is frequency. With a decrease in frequency, the wavelength must increase, since wavelength is inversely related to frequency as described by the equation (c = \lambda \cdot f), where (c) is the speed of light, (\lambda) is wavelength, and (f) is frequency.

Therefore, a decrease in photon energy leads to a decrease in frequency and an increase in wavelength. This highlights the direct relationship between the energy of photons, their frequency, and wavelength, confirming that the correct answer reflects the consequences of lowering photon energy in terms of its frequency and wavelength.