Concept:A sea route must connect ports that are accessible by ocean or sea navigation.
Explanation:Check whether every city on the route is a seaport or reachable by sea.
Option A: London → Moscow → Baghdad.
Moscow is an inland city with no direct sea access.
Baghdad also lies inland on the Tigris River, far from the sea.
Therefore, this route cannot be travelled entirely by sea.
Options B, C, and D connect major seaports through ocean waters.
Hence, they are valid sea routes.
Answer:A. London → Moscow → Baghdad