Which of the Following Was the Least Important Factor in the Fall

Which of the following was the least important factor in the fall of the Roman Republic?

A) An agricultural crisis undermined the farming class.
B) New wealth undermined old virtues such as steadfastness and the willingness to sacrifice personal interests for the good of Rome.
C) The Senate degenerated into a self-serving oligarchy and personal ambition led to civil war.
D) Outside pressure forced Rome to adopt a more efficient government.
E) Social harmony declined and the poor and idle masses withdrew their support of the state.