I easily knocked off answer choices A, B and C, but was left with D and E.
I don't see any inference to natural/positive law being concerned with the study of law being an 'economic' agent. So this is the trouble I have with (D) as the correct answer.
Further, CLS and Law & Lit emphasise the interdisciplinary approach -- employing disciplines such as anthropology and sociology. Given that these are new movements, and that they draw on interdisciplinary approaches, it seemed to differentiate these movements on that basis to some extent from the pre-70s approaches to the study of law.
Any help here would be appreciated!