After a Nuclear Reactor Fails, the Easiest Way to Determine

After a nuclear reactor fails, the easiest way to determine if there is an environmental release of radiation is:

A) To look at the reactor, it will appear radioactive to the eye.
B) To inhale the air, radioactivity has a distinct odor.
C) To listen for crackling sounds, as radioactive particles are emitted into the atmosphere.
D) None of the above