In a vertical thermosyphon re-boiler, it is due to the __________ difference that the circulation in the liquid occurs, between vapour-liquid mixture from the re-boiler and the liquid through the down-comer to the re-boiler.

In a vertical thermosyphon re-boiler, it is due to the __________ dif

1.	In a vertical thermosyphon re-boiler, it is due to the __________ difference that the circulation in the liquid occurs, between vapour-liquid mixture from the re-boiler and the liquid through the down-comer to the re-boiler.
A.	Density
B.	Pressure
C.	Temperature
D.	Concentration
Answer» B. Pressure