20. Though dealers insist that professional art dealers can make money in the art market, even an ____ knowledge is not enough: the art world is so fickle that stock-market prices are ____ by comparison.
(A) amateur's. .sensible
(B) expert's.. erratic
(C) investor's.. booming
(D) insider's.. predictable .
(E) artist's.. irrational
oa:
SPOILER: d