“The sole end for which mankind are warranted, individually or collectively, in interfering with the liberty of action of any of their number, is self-protection. The only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others.” The quotation illustrates John Stuart Mill’s _______.
A、Pleasure principle
B、Reality principle
C、Harm principle 
D、Liberty principle