Elements A and B form eutectic type binary phase diagram and the eutectic composition is 60 wt% B. If just below eutectic temperature, the eutectic phase contains equal amounts (by wt) of two solid phases, then the compositions of the two solid phases are
(a) 20 wt% B and 90 wt% B
(b) 30 wt% B and 90 wt% B
(c) 20 wt% B and 80 wt% B
(d) 30 wt% B and 80 wt% B