The mammoth structure overlooked the building.

The correct answer is C. huge.

A mammoth structure is a very large structure. It is much larger than a normal structure. It is so large that it can overlook other buildings.

A is incorrect because affluent means wealthy. A mammoth structure is not necessarily wealthy.

B is incorrect because tiny means very small. A mammoth structure is not very small.

D is incorrect because narrow means not wide. A mammoth structure is not not wide.