They traveled over the ice bridge from modern day Russia to modern day Alaska, and migrated from there some 10-11 thousand years ago is what is what is commonly accepted today.
C. By restricting their appearance.
Answer:variable - interval
Explanation: In the this scenario, The humanities instructor is using a variable-interval schedule of reinforcement. The instructor used the word 'surprise' meaning the time and date of the test isn't fixed and the quizzes will come up at unpredictable time intervals. This kind of reinforcement results in a steady response rate as it keeps students on their toes simply due to the fact that they have no idea of when the quizzes are coming up.
Ok so basically people would have problems accepting the Copernicus model because they church had believed that the earth was in the center of the universe. and that Sun, Moon, and stars — orbited Earth. they thought the Earth did not move at all. Copernicus believed that the sun was in the center and the planets moved around it. he even wrote a book about it but the church banned it cause they believed what they said was correct. it's a little messed up cause years after he died. they realized he was mainly correct about his theory. hope this helps.
The shape of the contitintes*
