Answer:
Correct answer is C. Low Countries.
Step-by-step explanation:
Option C is the only correct answer as it refers to area consisted of Netherlands, Belgium, but also parts of other countries in Western Europe, including France, Germany...
A is not correct as it refers to countries created in delta of certain rivers. Good example is Egypt (Nile).
B is not correct as it refers to countries that are not opened to seas or oceans - Andorra, Liechtenstein, Serbia...
D is not correct as it refers to mountainous countries, such as Nepal for example.