Answer:
C. A gap in the rock record
Explanation:
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.
Family with the wheel and what’s the next bar 3 question?
The answer I think to this is C. Eisenhower
Hope this helps in anyway? and sorry if it's wrong.