What describes the domain of y=tanx, where n is any integer?

Assuming you meant "where x is any integer":

is defined as , so it would be defined for every value of  except for those where , which is true when and , where is some integer. These values of  where  is undefined are both irrational; they cannot be expressed as a ratio between two integers, and so limiting the domain to integers makes sure that we'll skip over those points every time as  is increasing.

So, the domain of , when limiting that domain to the integers, is the set of all integers, .

It’s c. i’m almost sure