Some rivers begin in mountains or hills, where rain water or snowmelt collects and forms small channels, . At first, the channels are small and are called rills. As more water enters the channels they grow forming gullies (larger channels). The streams in the gullies eventually become big enough to form a river
Basal cell carcinoma. It’s the most common but least dangerous from of skin cancer. Hope this helps!
It releases certain chemicals
The answer is; a) they are naturally occurring.
