Question

what is the highest navigable lake in the world?
lake titicaca
lake ontario
lake baikal
the caspian sea

Explanation:

Lake Titicaca is located in the Andes Mountains at a high altitude and is navigable. Lake Ontario is one of the Great Lakes in North America with a relatively low altitude. Lake Baikal is the world's deepest lake but not the highest navigable. The Caspian Sea is the world's largest inland body of water but not a lake in the traditional sense (it's a salt - water lake / sea - like lake) and not the highest navigable.

Answer:

Lake Titicaca