In 1866 Congress refused to seat newly-elected members who were .
a.
former Confederate generals and political leaders
b.
African Americans
c.
Unionists
d.
supporters of Abraham Lincoln

A. former Confederate generals and political leaders

Explanation:

At that time, large portion of the Congresses believed that the confederate states still need to be punished for their treasons and for their refusal to free their slaves which caused the civil war between the northern and southern states,

They believed that allowing former confederates to join the congress will only empower those who wanted to turn the country backwards to the slavery era.

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.

the adoption by russian princes of the mongols' diplomatic rituals