The most important safety rule:
a. unloaded and grounded
b. finger off the trigger
c. know your backstop
d. muzzle always in a safe direction
D------ ;D
D. Slam-dunk. Prevents a disaster even in the event of almost any other mistake.
Definitely "D".
Or as I originally learned it -
Never point your rifle at anything that you do not wish to destroy.
D it is. As the guide says, even if a mistake is made and a round goes off then it goes where no one is at as long as the muzzle is pointed in a safe direction.