the decline of nationalism in European countries
- this is not true. Actually, nationalism arose only after the Age of exploration. 
the desire for knowledge about the non-European world
-yes, this is the correct choice!
 diplomatic exchanges with civilizations of the Americas
-not true! the exploration lead to the discovery of Americas, so they could not be influenced by it. 
 desires to meet savages from distant lands and learn about their culture
-no, Europeans at the time were not interested in this.