Answer:
A. Humans first lived in East Africa.
B. Migration occurred by land and sea
D. Humans crossed a land bridge to North America.
Step-by-step explanation:
Human migration is defined as the movement of humans from one place to another.
The earliest humans lived in East Africa about 3 million years ago and the earliest humans are known as Homo habilis. Richard Leakey found the first human species in the 1960s at Omo Kibish in south-western Ethiopia.
Migration occurred by land and sea in the earlier time. Humans used land bridges to move from one place to another and whenever sea level goes down they migrate through sea or water sources as well.
During the last ice age, humans crossed a land bridge to North America from Asia about 20,000 years ago. The land bridge is submerged underwater due to rise in sea levels.
Hence, the correct answers are "A, B, and D"