The word biased means A! Prejudice!
Now let's go down the list and compare - so for one - being intelligent doesn't exactly suit biased.
It supports only his point of view, although it may make him out to seem intelligent, it doesn't exactly leave room for anyone else's opinion.
Now, C! Understanding - not quite. Being biased is like judging a guy for having all tattoos and comparing him to all the criminals you've ever met - not fair.
And finally D! Not quite. Biased people may seem like there's a lot of hatred but it's not completely there, they just aren't properly educating themselves on everything else surrounding their point of view! So A would be your best bet!
I hope all is well, and you passs! Good luck, rockstar! (: