IN_ORDER_TO_ASSIST_SINKING_OF_WELL____________METHOD_IS_USED_IN_PNEUMATIC_CAISSONS.?$

Air pressure is reduced and Using explosive

IN_ORDER_TO_ASSIST_SINKING_OF_WELL____________METHOD_IS_USED_IN_PNEUMA

1.	IN_ORDER_TO_ASSIST_SINKING_OF_WELL____________METHOD_IS_USED_IN_PNEUMATIC_CAISSONS.?$
A.	Air pressure is reduced and Using explosive
B.	Using airlocks
C.	None of the mentioned
D.	All of the mentioned
Answer» B. Using airlocks