How many pore openings and sweat glands exist for each ridge unit?

c

explanation:

a lot of people sadly don't know the best way to learn is cheating off of your friends or this amazing thing called google

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.