Dr. F Went noted that if coleoptile tips were removed and placed on agar for one hour, the agar would produce a bending when placed on one side of freshly cut coleoptile stumps. Of what significance is this experiment?
(a) It made possible the isolation of auxin
(b) It is the basis for quantitative determination of small amounts of growth-promoting substances
(c) It demonstrated polar movement of auxins
(d) Both a and c