Answer:
The Dardanelles, is the right answer.
Explanation:
A campaign that took place in the Gallipoli peninsula in the period between 17 February 1915 to 9th January 1916, came to be known as the Gallipoli campaign. This campaign was launched by the allies to weak the Ottoman empire, by establishing their control over the straits that presented a supply route to Russia. The attack made by the Allies on Ottoman forts at the entrance of Dardanelles in February 1915 met a failure. The allies forces in April 1915 tried to capture Constantinople, the capital of the Ottoman empire.
