Questão de Língua Inglesa

Which option completes the sentence below correctly? Norwegian explorer and writer Thor Heyerdahl had attempted to prove that the Polynesian islands could have been colonized ___ people ___ South America ___ pre-Colombian times. (Adapted from <https:l/www.deeperblue.com/fantastic-voyages-mythlegend-and-the-recreation-of-ancient-boats>}