According to the regulations for life boat falls，which action must be taken at 30-month intervals?（）

A.grooved wheel in a block
B.line to hold a lifeboat next to the embarkation deck
C.partial load of grain
D.seaman's knife

A.a heavy anchor with an extra long line used to anchor in deep water
B.a cone shaped bag used to slow down the wind drift effect
C.a padeye to which the sea painter is made fast
D.made of wood if it is of an approved type

A.the line attached to the tack of the lugsail
B.the emergency rudder
C.a canvas awning
D.the aftermost seating