Foster: Many species of extremely large North American mammals became extinct during the last ice age, which was also the time of the first human migration to North America. These species could not survive the dramatic changes wrought by this human migration. Fisch: Those extinctions were caused by the dramatic shift to a harsher climate. The climate changed so rapidly that the species could not adapt. Which one of the following, if true, most strengthens Fisch's argument? ['Similar species living in parts of the world where there were dramatic changes in climate did not become extinct.', 'The huge size of the mammals made it difficult for them to migrate the great distances to milder environments.', 'Archaeological evidence reveals that the human migrants had a number of different kinds of large weapons.', 'Human migration to other previously isolated areas has resulted in mammal species becoming extinct.']