CIA needs a killer and it subjects three persons to a test.
Agent of CIA speaks to the first person, a man: "Take this pistol. In the other room there is your wife. Kill her."
The man: "No, I can't do it!".
Agent: "You are not reliable. Goodbye."
Agent of CIA speaks to the second person, a man again: "Take this pistol. In the other room there is your wife. Kill her."
The man takes the pistol, enters in the other room, comes back and says: "No, I can't do it...".
Agent: "You are not reliable. Goodbye."
Agent of CIA speaks to the third person, a woman: "Take this pistol. In the other room there is your husband. Kill him."
The woman suddenly takes the pistol, enters in the other room, she doesn't close the door either. The agent hears all the shots, then he hears screams, the noise of a violent fight, the noise of broken furnitures.
The woman comes back and says: "Your bullets were false. I had to kill that bastard by the chair!".