Central America is a long and narrow strip of land which is located between two bodies of water and which connects two pieces of land - we call such a formation an "isthmus" - this is the correct answer.
The Suez canal is also such an isthmus and so is Manila, the capital of the Philippines.
An estuary is where salt water and fresh water meet. Estuaries are usually found at the edge of the coast, where the ocean water, or salty water, meets river, lake, any fresh water source, water.
A tributary is something completely different. It is a, usually smaller than the main river or lake, river/stream stemming off a bigger river or lake, or flowing into that river or lake.
Portugal is a country full of wonders — charming castles, pristine beaches, and a metropolitan capital spattered in remnants of the past. Its buildings are covered in thousands of intricately decorated tiles in countless colors and patterns. ... The words to describe Portugal are endless.
