Aisha if I were you, I wouldn't call BBC "neutral". As you have mentioned, Al jazeera being pro Arab, I think you should emphasize the same way that BBC is more leaned to reflect the viewpoint of its govt and allies.
In this particular case BBC is optimistic, because it needs to show the audience that since British or allies are in Afghanistan, the drug growing has decreased sharply.
There are countless news, really countless, where very optimistic news coming from countries which are not on good radars of BBC are presented in dismal pessimistic way.
Headings, choice of words, accompanying pictures, background scenes--> the message that BBC conveys to its viewers is never merely a fact but an opinion!
Otherwise the essay is well written.