When an object like a piece of graphite is heated to 1000 K, it glows red. When the temperature is increased to around 3000 K, the color of emitted light becomes orange. What is the reason for this change in color?

a. The speed of the photons (quantized packets of radiant energy) increases with increasing temperature.

b. The average wavelength of the photons emitted increases with increasing temperature.

c. The average energy of the photons emitted increases as the temperature increases.