ANS:A - 723

The eutectic temperature represents the lowest possible melting point of an alloy mixture, occurring when the composition of the mixture is precisely at the eutectic composition. In the case of the iron-carbon system, at a temperature of 1147°C, the eutectic reaction occurs, leading to the formation of a eutectic mixture consisting of austenite and cementite phases. This reaction marks the point where the liquid phase transforms directly into a mixture of solid phases. Therefore, the correct eutectic temperature for the iron-carbon system is 1147°C, not 723°C.