Final answer:
The Bosphorus Strait separates the two sections of Constantinople (Istanbul) and serves as the gateway between Europe and Asia.
Step-by-step explanation:
The body of water that separates the two sections of Constantinople is the Bosphorus Strait.
Constantinople, now known as Istanbul, was strategically important due to its control over the Bosphorus Strait and the Dardanelles Strait. These straits connected the Mediterranean Sea with the Black Sea and served as the gateway between Europe and Asia.
The Bosphorus Strait separates the European and Asian parts of Istanbul, and it plays a crucial role in trade and transportation, connecting the Sea of Marmara to the Black Sea.