Which of the Following Is a Main Argument of Market-Clearing

Which of the following is a main argument of market-clearing theories of the labour market?

A) Competitive labour markets can be relied upon to eliminate all unemployment.
B) Labour markets will clear and involuntary unemployment will thereby be eliminated.
C) All unemployment is most easily corrected by government intervention in the economy.
D) All unemployment arises from firms being unwilling to demand labour services.
E) Labour unions are necessary elements in reducing unemployment.