Education in the critical faculty is the only education of which it can be truly said that it makes good citizens.

=Education in the critical faculty is the only education it can be truly said that it makes good citizens of which

参考译文(1)：具有批判性性思维能力的教育才是真正能说是它是可以教育出好市民的唯一教育。

参考译文(2):准确地说，教育的关键职能在于，只有它才能培养出好的公民”

解析：关系代词which代替先行词“the only education”并在定语从句作状语成分。结构为make sth of sth

markets do function quite efficiently most of the time，summing up vast amounts of information into a single number —— the price—— on the basis of which millions of decisions are made.

of which为介词加关系代词作定语,与后面was made构成搭配，was made of which