The answer is letter c.
It can be both natural and human source of pollution. There are times when the intense heat can
trigger a brush fire and can expand depending on how strong the wind
blows. It can be caused by humans. it could due to carelessness of people leaving
flammable materials unchecked. Or using too much fuel that when lit would cause
a brush fire that would expand into a wildfires. The smoke from it pollutes the air.
The correct answer is A. When the subject of a sentence is singular, add "_s" to the base form.
An easy example is "to exist", the base form is "exist" and A strawberry exists shows that you add s when a singular subject is used.
I think it is adverb clause because of the word "hardly" which emphasises the ripple of the water
Well what do you mean haha