9. Name the feature shown above that is the longest chain of mountains in the world.

The mid-ocean ridge The Andes

Explanation:

This answer is more complicated than it appears, because it depends on what is being asked in the questions. If we are considering all mountain ranges on Earth, the Mid-Ocean Ridge system is by far the longest, being at least seven times longer than the longest mountain range above water.

This distinction belongs to the Andes mountains, which at over 6000 kilometres in length are the longest mountain range found exclusively on continents.