There Are a Number of Layers in the Atmosphere Where

There are a number of layers in the atmosphere where oxygen molecules are broken into atoms that can combine with other O₂ molecules to make ozone (O₃) . Why is it that there is only a specific region/layer where ozone is made in any significant amount?

A) The reaction is faster at higher altitudes.
B) The concentration of O₂ is not large enough at higher altitudes.
C) The energy from the sun is not strong enough at higher altitudes.
D) The molecules cannot breathe at higher altitudes.
E) The reaction is slow at higher altitudes.