In at the Earth's surface, warm air expands and rises, leaving behind what is known as an area of proate what is known

the correct answer is c   with the systems

the scientific method.

the correct answer is option d.

an appositive is a noun, noun phrase or noun clause which follows another noun or noun phrase in order to describe it or name it another way. they are usually used between commas, brackets or dashes.

the example sentence with the correct use of commas is the following:

her uncle, the man over there in the red shirt, owns the hardware store in town.