What is the primary achievement of John Cabot?

John Cabot's primary achievement was claiming Newfoundland for England. This event, which took place in 1497, marked one of the earliest European explorations of North America, establishing a precedent for future English claims to territory on the continent. Cabot, an Italian navigator working under an English commission, was aiming to find a westward route to Asia but instead encountered the North American coast. His journey contributed significantly to the onset of English involvement in the transatlantic ventures and colonization efforts in the New World.

The other options relate to different geographic discoveries or colonial efforts that were not part of Cabot's achievements. For example, the Grand Canyon, known for its immense size and geological features, is located in Arizona and was explored much later. Quebec, founded by Samuel de Champlain in the early 17th century, is associated with French exploration and settlement rather than Cabot. Lastly, sailing around Cape Horn pertains to routes taken much later by explorers seeking to navigate around South America, which was not part of Cabot's expeditions.