The changes in the channel’s sands and buoys on this coast are （） this chart can not be considered as a safe guide of the channel．

A.To consider
B.To check
C.To examine
D.To agree with

A.cylindrical projection
B.simple conic projection
C.polyconic projection
D.rectangular projection

A.after every major hydrographic survey of the area covered by the chart
B.when there are numerous corrections to be made or the corrections are extensive
C.when a low-stock situation occurs and minor corrections are made
D.every two years to update the magnetic variation information