Which one of the following most accurately characterizes the author's attitude toward placebo treatment?
reserved advocacy
Only choices (a) and (b) have any real merit. Although the passage has a detached, third-person style, the author nonetheless, does present his opinions— namely that placebos work and that their use should be expanded. However, that advocacy is reserved, so the correct answer is (a).
The other choices can be quickly eliminated: Given the human ego, we are unlikely to admit that we don’t understand the subject we are writing about. This eliminates (c).
“Zealous promotion” is too strong; “promotion” itself is probably too strong. This eliminates (d).