NSD scholars testify frequently before congressional committees and provide expert
reports to all branches of government, which are cited in the national media more
often than any think tank.
A. provide expert reports to all branches of government, which are cited in the
national media more often than any think tank.( Reference to "which" is a little ambiguous, looks like "which" is referring to government...Incorrect comparison to think tank )
B. provide expert reports to all government branches, which are cited in the national
media more often than any other think tank ( reports are compared and hence "any other think tank " is wrong here.)
C. provide expert reports to all branches of government, and are cited in the nation's
media more often than are any think tank ( Meaning is lost and awkward construction )
D. provide all branches of government with expert reports, which are cited in the
national media more often than those of any other think tank - Correct
E. provide all branches of government with expert reports, as well as cited in the
national media more often as are those of any think tank ( awkward construction )[/quote]

D is the clear winner.
A and B is out for Which wrongly pointing to Government.
Option C, We are not sure what is cited , Reports or NSD.
Option E - As well as is a choice when we try to mean something like .. Ron as well as Petra ...

C also has "They do X, and they do Y, and they do Z." When the things listed can otherwise be parallel, I would expect "They do X, Y, and Z."