Which of the following should be considered when sighting in a rifle?

a, gravity, air resistance and energy loss all have an effect on the bullet's trajectory gravity, air resistance and energy loss all have an effect on the bullet's trajectory

b, a rifle sighted to hit a target at 100 yards will also hit the center of that target at 50 yards a rifle sighted to hit a target at 100 yards will also hit the center of that target at 50 yards

c, avoid using a steady rest when firing a rifle since this will affect the bullet's trajectory avoid using a steady rest when firing a rifle since this will affect the bullet's trajectory

d, breathe normally while squeezing the trigger. holding your breath will affect the bullet's trajectory. breathe normally while squeezing the trigger. holding your breath will affect the bullet's trajectory.