It cant be A because if you go to Google, it states that there are the "Shebshi Mountains, mountain range in eastern Nigeria" (Britannica.com).
A likely natural feature in an extremely densely populated area would be a well watered, fertile plain. An example is the Northern plain of India also called the Indo - Gangetic plain. It s on one of the world's most densely populated area per square kilometer. This plain is formed from the flood plains of three great river systems - the Indus, the Ganga and the Brahmaputra. The soil cover in the plain is rich and fertile and water is found in plenty. These factors combined with a favorable climate makes it one of the most intensely farmed and populated areas in the globe.
Well, it certainly can't be any of the countries on that list,
because there is no list !
The Hawaiian island these are an island that are 60 west longitudes of the south of the equator.
The valley of Mexico is a highlands plateau in central Mexico roughly coterminous with the Present-day Mexico city and the Eastern half of the State of Mexico
