Which is not one of the four pillars of democracy?

opportunity for education
equality before the law
property rights
the citizen's freedom
voting rights

The four pillars of democracy are justice, equality, freedom and representation. On the choices given, its property rights that does not belong to the four pillars of democracy. Property rights belongs to the four pillars of Legal Empowerment of the Poor hosted by the United Nations Development Programme.

To justify, opportunity for education  and equality before the law falls under Equality. Under democracy everyone are given the same basic opportunities to be happy and succeed. The citizen's freedom falls under freedom and voting rights falls under representation that ensure people will have the right to choose who represents them in the government.