Data backup and collaboration.
Answer:
You will get compile error
Explanation:
<span>The Union victory in the Civil War may have given some 4 million slaves their freedom, but African Americans faced a new onslaught of obstacles and injustices during the Reconstruction era (1865-1877). By late 1865, when the 13th Amendment officially outlawed the institution of slavery, the question of freed blacks’ status in the postwar South was still very much unresolved. Under the lenient Reconstruction policies of President Andrew Johnson, white southerners reestablished civil authority in the former Confederate states in 1865 and 1866. They enacted a series of restrictive laws known as “black codes,” which were designed to restrict freed blacks’ activity and ensure their availability as a labor force now that slavery had been abolished. For instance, many states required blacks to sign yearly labor contracts; if they refused, they risked being arrested as vagrants and fined or forced into unpaid labor. Northern outrage over the black codes helped undermine support for Johnson’s policies, and by late 1866 control over Reconstruction had shifted to the more radical wing of the Republican Party in Congress.</span>
The answer is D, because it's called a back-up.
