Which of the following is true of the U. S. criminal justice system?
Approximately 90 percent of all cases begin and end with a guilty plea.
The Constitution does not specify the size of a jury, but tradition has set the number at twelve.
Unanimous votes of juries are required for a criminal conviction.
All of the above are true.

3 ) Unanimous votes of juries are required for a criminal conviction.

Explanation:

All 12 jurors must agree, they must be unanimous. Recently  I read a news about an American black man convicted of murder and sentenced to death, while on death row, his execution date approached, but the case was dropped against him due to the fact that there was not a black jury among 12 jurors.

then its a law the end

25. twelve tables

26. having important positions chosen by lot