Upside and downside can mean a positive and a negative aspect of something, respectively. However, none of the options here present a couple of something negative and something positive: so I think we need to use the local meaning. So our analogy is:
on one extreme of some location (on the upper side): on the other extreme.
Therefore the best other couple is outside and inside: they also show two opposite locations.
It depends on what you want to write about, as the question includes the word appropriate, B wouldn't be right, C is a bit complicated, and A is just not correct. I'd say its none of the above
Its the third sentence,because a plural word hast to have a dash, not a space/
