The answer is A, or Ending enslavement would be unconstitutional.
Conquered people often times became prisoners or servants to the elite of the land they now belonged to.
Slaughtehouse-Five has a very peculiar structure. Vonnegut's idea of time is reflected in it, it's not linear. As a result, there are a lot of contrasting images. An example of this is the contrast between the following Paradisiac image:
<em>Under morphine, Billy had a dream of giraffes in a garden. The giraffes were following gravel paths (...) Billy was a giraffe, too (...) The giraffes accepted Billy as one of their own, as a harmless creature as preposterously specialized as themselves. Two approached him from opposite sides, leaned against him. They had long, muscular upper lips which they could shape like the bells of bugles. They kissed him with these. They were female giraffes-cream and lemon yellow. </em>
With an quite calamitous image not too far from that part of the book:
<em>Rosewater was twice as smart as Billy, but he and Billy were dealing with similar crises in similar ways. They had both found life meaningless, partly because of what they had seen in war. Rosewater, for instance, had shot a fourteen-year-old fireman, mistaking him for a German soldier (...) And Billy had seen the greatest massacre in European history, which was the firebombing of Dresden. </em>
Yes, white collar crimes although non-violent break laws such as fraud and embezzlement. if left unpunished, that person could potentially steal millions of more dollars from innocent, unsuspecting people.