The process of mountain building is called Orogeny.
My best guess would be c because b makes no since we as humans do not have photosynthesis and are considered living organisims, d is also wrong because the brain requires oxygen, and its not a because the brain is made of cells.
The root tip allows the plant to grow deeper into the soil
They dont release any oil
they "preen" their feathers with their beaks not put oil on them