Rain and snow will occur in low air pressure.
When the pressure of the air is low, the air rise upward in the atmosphere and gets cool and condenses. The condensation causes the formation of clouds from water droplets and snow particle around the dust particle in the sky and at last the the condensation of water vapor causes the formation of rain.
I believe the answer is Gene splicing because they remove specific genes in order to create a transgenic organism.
I hope this helps!
A. The arrangement of particles within the watermelon changed.