Answer:
Option (D)
Step-by-step explanation:
Isthmus refers to the tapering strip of land that connects two bigger landmasses. This narrow land occurs where there is the presence of the seas on both sides. For example, Isthmus of Kra that connects the peninsular Malaysia and the southern part of Thailand.
This type of landforms are generally formed near the seas and they can be formed by volcanic activities, that create island chains by obstructing the channel and accumulating sediments. The Isthmus of Panama formed in this way that is shown in the given image.
An isthmus can also form due to the lowering of sea level because it will expose more of its land area above the water surface.
Hence, the correct answer is Option (D).