To prove that if set B is included in set C, then the power set of B is included in the power set of C, one can start with the definitions of power sets and subsets. The power set of C contains all subsets of C, which inherently includes all subsets of any subset of C, including B. Therefore, every subset of B, which constitutes the power set of B, is also a subset of C. This leads to the conclusion that the power set of B must be included in the power set of C. The argument is formal and aligns with set theory principles.