Directions: Read the following passage and answer the question that follows:

The River of Doubt is a black unchartered tributary of the Amazon that snakes through one of the most treacherous jungles in the world. Indians armed with poison-tipped arrows haunt its shadows, piranhas glide through its waters, boulder-strewn rapids turn the river into a rolling cauldron. After his humiliating election defeat in 1912, Roosevelt set his sight on the most punishing physical challenge he could find, the first descent of an unmapped, rapids-choked tributary of the Amazon. Together with his son Kermit and Brazil’s most famous explorer accomplished a feat so great that many at the time refused to believe it. In the process, he changed the map of the western hemisphere forever.

The antonym of the word ‘descent’ is