"What I must do is all that concerns me, not what the people think. It is easy in the world to live after the world's opinion; it is easy in solitude to live after our own; but the great man is he who in the midst of the crowd keeps with perfect sweetness the independence of solitude."

Which assertion does this quotation support?
A. People should be generous.
B. People should live in solitude.
C. People should think for themselves.
D. People should keep their opinions to themselves.