Take another look at this source.
Choose the right word or phrase to complete the
sentence.
The codes made it possible for white people to
force children into
slavery.
DONE
labor contracts.
apprenticeships.

Labour contract

Explanation:

Code ensues a legal writing with uterior negative consequences; so that it won't be seen as outright slavery because it is enshrined in a 'Labour Contract's clause.

c) troops march forward in close formation against newer, more accurate weapons