Final answer:
A common restriction in the black codes was that formerly enslaved people could not work for more than one employer, restricting their labor freedom and keeping them in a state similar to slavery. The correct answer is option C.
Step-by-step explanation:
The common restriction included in the black codes was that formerly enslaved people could not work for more than one employer, effectively limiting their autonomy and ability to improve their work conditions.
Black codes were designed to maintain a supply of cheap labor and prevent integration of the races after the Civil War. These laws heavily regulated the lives of African Americans, including labor restrictions that bound them to their employers, resembling antebellum slavery conditions.
Among other restrictions, black codes denied basic civil rights, including the right to testify against white people in court, serve on juries, bear arms, vote, and the freedom of movement, essentially enabling 'slavery by another name' through vagrancy laws and restrictive labor contracts.