ANS:A - Agitated film evaporator

The concentration of rubber latex is typically carried out using a long tube vertical evaporator. Rubber latex concentration involves removing water from the latex to increase the concentration of rubber solids. Long tube vertical evaporators are commonly used for this purpose in the rubber industry. In a long tube vertical evaporator, the latex is pumped to the top of the evaporator, where it is distributed across a series of long vertical tubes. Steam is introduced into the tubes, causing the water in the latex to evaporate. The concentrated latex is collected at the bottom of the evaporator. Long tube vertical evaporators provide efficient heat transfer and high evaporation rates, making them suitable for concentrating rubber latex to the desired solid content.