Your answer would be D) Stromatolites. hope this helps :)))!
The world's tallest artificial structure is the 829.8-meter-tall (2,722 ft) Burj Khalifa<span> in Dubai. The building gained the official title of "Tallest Building in the World" and the tallest self-supported structure at its opening on January 9, 2010.</span>
It has the Nile river in the east, the Sahara desert and the Atlas Mountains which are in the west.
It occurs at the equator mostly
