Who made the cake

A．The removal of water in food helps prevent it from going rotten.
B．The open-air method of drying food has been known for hundreds of years.
C．In the course of dehydration, the temperature of hot current coming from entry to exit is gradually going up.
D．The process of drying liquid is much m-ore complex than that of drying solid food.

A．emigrants
B．immigrants
C．talents
D．emigration