Concept:Identifying relief features by using their positions on a map.
Explanation:The map shows part of the Nigeria\u2013Cameroon borderland.
The feature marked Y is located in the extreme north-eastern section of Nigeria.
That region is part of the highlands known as the Mandara Mountains.
The Mandara Mountains form a prominent range along the border, running south of Lake Chad.
Obudu Plateau and Obon Hill are found in south-eastern Nigeria, far away from the area shown.
Alantika Mountain also lies on the eastern border, but it is positioned farther south, closer to the Benue valley.
Comparing the location of Y with these known relief features confirms that Y is not one of the south-eastern uplands.
Therefore, the only correct feature that matches the position of Y is the Mandara Mountains.
Answer:D. Mandara Mountain.
