What is it i’m really really really confused about it lol

it would be D

So, when they say quantities that combine to make 0, that means you have to lose, and then gain the same amount back.

If you look at all the other choices, they either keep on gaining or they don't gain the same amount they lost

Think about it as breaking even.  You aren't actually gaining anything if you are gaining back the exact same amount you lost.

80x^8−68x^6+16^5−20x^4−4x^3+8x^2

hope i'm right lol

it is 10.6 according to my calculations