Slavery tolerated because of "necessity" means that you do not really want to do it, but you think you must do it. An example is when you have a farm and you need people to work on it. The trouble behind this scenario is that your farm isn’t making money to pay your farm helpers their proper wages, so you resort to slavery. In this case, you do not need money for salaries because your farm is doing well to keep your slaves clothed and fed.
Slavery affirmed as a "moral right" is when you think it is your right to be the master and the slaves deserves to be slaves.
The correct option is this: ASSIMILATE NATIVE AMERICANS INTO THE DOMINANT CULTURE.
Dawe's Act was enacted in 1887. The act authorized the American president to survey the American Indian tribal land [reservation land which was held in common by the member of the Indian tribe] and divide it into allotments among the Indians. This law changed the legal status of the Indians from tribal members to individuals who are subject to federal laws.<span />
<span>They were looking for wealth.
They sought a new route to Asia.
They attracted a great deal of interest in Spain.</span>