Which of the Following Scenarios Would Threaten the Success of Mutual

Which of the following scenarios would threaten the success of mutual nuclear deterrence?

A) The leader of Pakistan becomes suicidal.
B) France doubles the size of its nuclear arsenal.
C) Iran obtains nuclear weapons.
D) The United States puts ballistic missiles on train cars that move around the country.
E) Russia increases the strength of the silos holding its nuclear missiles.