Final answer:
The Black Sea has the greatest agricultural productivity along its coastline due to its extensive network of canals and waterways, which facilitate irrigation and transportation.
Step-by-step explanation:
Among the bodies of water mentioned, the Black Sea has the greatest agricultural productivity along its coastline. The region around the Black Sea benefits from the extensive network of canals and other waterways, such as the Volga River, which flows into the Caspian Sea and is connected to the Black Sea through a canal via the Don River. This promotes agricultural activities, irrigation, and transportation of goods. In contrast, areas like the Caspian Sea face challenges due to pollution and overfishing, while the Arctic Ocean is not conducive to agriculture due to its frigid climate and short growing season. The Baltic Sea's coastline is not as agriculturally productive as the Black Sea's, mainly due to its colder water temperatures and lower salinity than the Black Sea, affecting the types of crops that can be grown nearby.