Final answer:
Roger and Maurice kick over the sand castles of the younger children to assert dominance and out of boredom.
Step-by-step explanation:
Roger and Maurice kick over the sand castles of the younger children A) To assert dominance and B) Out of boredom.
By kicking over the sand castles, they demonstrate their power and control over the younger children. Additionally, they might do it out of a lack of entertainment or the need for excitement.
It may not be in C) a fit of rage as this suggests anger as the motivation, nor as D) part of a game, as the intention is not to play but rather to dominate or alleviate boredom.