What does it mean when world war i is referred to as a "total war”?

Lot's of advances in technology was made during this war. Many of the tactics are still used today I believe. Don't know if this helps or not.

the answer is b for brother

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.