Economy of evaporators used for concentrating sugarcane juice is
- $\frac{kg\:of\:concentrated\:juice\:produced}{kg\:of\:steam\:supplied}$
- $\frac{kg\:of\:steam\:supplied}{kg\:of\:sugarcane\:juice\:fed}$
- $\frac{kg\:of\:water\:vaporized}{kg\:of\:steam\:supplied}$
- $\frac{kg\:of\:sugarcane\:juice\:fed}{kg\:of\:water\:vaporized}$