If superheated vapor enters an open feed water heater at a rate of 5 lbm/s, mixing with water at a rate of 3 lbm/s, what is the mass flow rate of fluid leaving the feed water heater?

A) 2 lbm/s
B) 3 lbm/s
C) 5 lbm/s
D) 8 lbm/s