The speed of a photon, regardless of its color or frequency, is always the speed of light. This is a fundamental constant in physics, denoted by the letter 'c', and its value is approximately:

c = 299,792,458 meters per second (m/s)

Here's why:

* Electromagnetic Spectrum: Light, including red light, is a form of electromagnetic radiation. It travels as waves and can have various frequencies, which determine its color.

* Speed of Light is Constant: The speed at which these electromagnetic waves propagate through a vacuum is constant. This speed is the speed of light.

Therefore, the speed of a photon of red light with a frequency of 4.3 x 10^14 Hz is approximately 299,792,458 m/s.