(E) is wrong because "key". Who knows what the "key" to maximizing profits are? Probably to drive all your competitors out of business and then price your milk for their weight in gold. So, that's an excellent reason to eliminate (E) off the face of the planet, choose (B), and move your ass along.
But waaaaait, you're whining, I don't like (B) because it says "introduced for the sake of" maximizing profits. Well, why was the practice introduced? Just because the first sentence out of the dairy farmer's mouth talks about the cows' well being doesn't mean that his actions were motivated by a concern for the cows' well being. I can talk all day about how I love cows and then do everything according to a profit motive.
So you want to make sure you're not fooled into thinking that just because a statement was uttered first, that means it motivates anything.
More directly, we're told that the action was "intended increase blood flow to the utter". What in the world would motivate the farmer to want to do that? For the cow's comfort? That's a stretch. Especially because the farmer tells us that increased blood flow to the utter boosts milk output which increases profits. Far less of a stretch to assume that the "intention" carries through to profits.