Use what you know about the case of Gideon v. Wainwright to determine which of the following phrases is etched on Gideon's gravestone.
A - Each era finds an improvement in law for the benefit of mankind.
B - Poverty is its own protection against abuses of government.
C - The question is not what have we done, but have we done it justly?
D - Power seeks the lowest forms and exploits their weaknesses.