Answer:
To prove he had made landfall on the shore of North America
Explanation:
The social values that would have led Jacques Cartier to kidnap the sons of the Iroquois host at the Gaspe Peninsula and take them to Europe are "To prove he had made landfall on the shore of North America."
During the period in which Jacques Cartier first explored North America, many explorers and voyagers had made quick money in lying about sailing to North America, whereas they only sailed out of sight and after sometimes come back to tell the unfortunate tales after pocketing their proceeds.
Hence, to prove he has reached North America and have seen people there, he kidnaps the sons of the Iroquois host at the Gaspe Peninsula and takes them to Europe