Europeans couldn't travel into the interior of Africa in order to take it over because of the African-ruled trade, couldn't navigate violent rivers, or overpower their strong armies. Disease also held them back.
The Caste system was based on the religion of Hinduism, whilst in the Feudal system the Roman Catholic Church and in it's beliefs were followed. The highest class for the Feudal system was the King; but in the Caste system it was the Brahmins (Priests), although the king was part of the second tier the Kshatriyas. The Feudal system existed during the middle ages and when it ended it caused the end of the middle ages. The Caste is still being followed today in India.
The answer is Marie Curie
All of these statements are correct.