Go ahead and read the argument for Section 2, number 10 of the June 2007 LSAT. The question asks "Which one of the following most accurately expresses the main conclusion of the argument?" As I've said before, it's critical that you predict the answer choice on a main conclusion question in advance. So stop before you look at the answer choices and try to make a prediction. Hint: There's one word in the argument itself that is an awfully big clue. Can you find it? The word is "should." On the LSAT, any time a speaker says that someone should or should not do anything, they're almost always making their conclusion. "Should" is a normative and usually subjective judgment rather than anything that is objectively true. Any time you say we "should" do something, you usually have to back it up with evidence. Example: "We should go see Drive." "Really? I heard it sucked, why would we want to do that?" "Well, it got a good rating on Rotten Tomatoes, and... and... and..."
This argument follows the same pattern. The conclusion is "double-blind techniques should be used." How come? Well, because 1) they help prevent misinterpretations, and 2) scientists should try to avoid such misinterpretations... THEREFORE double-blind techniques should be used.
Since the rest of the argument provides reasons for why we should do something, I know for sure that the conclusion is "double-blind techniques should be used." Now all we have to do is find that in the answer choices.
A) Hmm. This isn't what I'm looking for, and furthermore the word "objectivity" wasn't even mentioned in the argument. I doubt this can be the answer.
B) This basically means "double-blind techniques should be used," so it matches nicely with my prediction. I love this answer, and I hope the rest of the answers suck so I can confidently pick B.
C) This isn't supported at all by the evidence. How do we know that scientists are not already extremely diligent, and avoid this type of error (possibly using double-blind techniques)?
D) This is definitely a premise of the argument, but I don't think it's the conclusion since it doesn't say anything about double-blind techniques.
E) This is probably the second-best answer, but it's a trap. The problem with this answer is that there's no should here. Saying something is "effective" isn't the same thing as saying we "should" do it. (Punching someone is an effective way to make them mad, but that doesn't mean we should do it.) Note that answer B said "it is advisable" which is a lot closer to "should." B is our answer.