Ronald Coase Was Awarded the 1991 Nobel Prize in Economics

Ronald Coase was awarded the 1991 Nobel Prize in Economics primarily for addressing problems related to externalities.Which of the following describes Coase's work?

A) Coase argued that government intervention is necessary to achieve economic efficiency in markets that are affected by externalities.
B) Coase proved that economic efficiency cannot be achieved in a market that is affected by positive or negative externalities.
C) Coase argued that under some circumstances private solutions to the problems of externalities will occur.
D) Coase proved that a competitive market achieved a greater degree of economic efficiency than a non-competitive market when externalities occur.