The first sentence is a fact of a study, not a conclusion. Think "if somebody said this to me, would i ask them 'why do you think that.'" If you would ask them "why do you think that" then it IS a conclusion. If not, its likely a premise or a fact or something else entirely. So, if someone said "a study shows that people who keep daily diet records are far more successful at losing weight than people who don’t keep track of what they eat" you wouldn't say to them "why do you think that?" You would instead say something like "oh, can I see that study to verify?" On the other hand, if they said "I think weight loss plans fail because people lie about what they actual eat if they don't write it down" you might end up asking them "why do you think that?" to which they would respond "well, I read this study that said ___." So, the answer to this question would therefore be D, as the first bolded sentence is a fact or premise while the second bolded sentence is a more specific finding that corroborates the belief of the scientists.