Concept:A sea route is a navigable path across oceans or seas that links coastal ports.
Explanation:Option D, London-Moscow-Baghdad, is not a sea route.
Moscow is an inland city, and Baghdad is also far from the sea.
A sea route must connect seaports that ships can reach directly.
Options A, B, and C each link major port cities through ocean waters.
Therefore, the only route that cannot be travelled by sea is London-Moscow-Baghdad.
Answer:D. London-Moscow-Baghdad