American students during the Cold War often practiced air raid drills because A. they were hoping to contain the spread of democracy
B. they were preparing to invade Cuba
C. they were prepared for a possible nuclear war
D. they wanted to prove their loyalty to the U. S.

C. they were prepared for a possible nuclear war

Explanation:

it refers to race, i am pretty sure this was a popular term in nazi germany or something.

2. a land bridge connected asia and north america thousands of years ago.

4. crossing the land bridge would have been simple for the first migrants.

5. people might have crossed a land bridge while hunting animals.