Which of the Following Is Not an Element Common to the Various

Which of the following is not an element common to the various schools of liberalism?

A) International institutions are important actors that can mediate disputes among states.
B) Establishing stable democratic governments will enhance the prospects of peace.
C) States' concerns about relative gains impede cooperation.
D) Free trade gives states a material incentive to maintain peaceful relations.
E) All of the statements above are common elements in the various schools of liberalism.