Why do Coast Guard vessels today monitor straying icebergs that drift toward ship routes?
A. To gather more information on the locations of ships and how close they are to danger
B. To find out in which part of the ocean most icebergs form and how long they stay solid
C. To make sure passenger ships stay in the winter lane and do not head further north
D. To keep track of the icebergs' whereabouts and prevent them from getting near ocean liners
