Explanation:
Option 1: A strait is a narrow channel of water that connects two larger bodies of water, such as two seas or an ocean and a sea. It is not concave in shape like a bay.
Option 2: A sound is a wide sea or ocean inlet that is usually longer and narrower than a bay. It is also not concave in shape.
Option 3: A bay is a wide inlet of the sea that is usually concave in shape. It is often surrounded by land on three sides. This aligns with the correct answer provided.
Option 4: A fjord is a narrow inlet of the sea that is surrounded by steep cliffs. Unlike a bay, it is not as wide and usually has a U-shaped profile.
The correct answer is option 3 - a bay.