ACCorDing to thE Author, CliniCAl triAls oF vitAmin supplEmEnts______.
A．oFtEn rEsult in mislEADing ConClusions
B．tAkE timE AnD will not proDuCE ConClusivE rEsults
C．shoulD BE ConDuCtED By sCiEntists on A lArgEr sCAlE
D．AppEAr to BE A shEEr wAstE oF timE AnD rEsourCEs