Which one of the following is applicable to collision-coalescence process of precipitation?

In colder clouds: droplets formed by Bergeron mechanism. But, in many parts of the world the air is too warm for ice crystals to form. This being the case, rain and snow cannot develop following the Bergeron Process. Instead, tiny droplets form as they collide into one another creating larger and larger droplet, this is known as collision-coalescence process. So, warmer clouds are associated with this keyword.