Final answer:
The missing part of the question could be any of the options listed, as they are all essential for determining a projectile's motion. The provided references deal with projectile motion in physics, outlining how muzzle velocity and air resistance affect the bullet's trajectory.
Step-by-step explanation:
The missing part of the question involving Bullseye Bill, who fires his rifle at a target 200 meters downrange, could be any of the options listed: Velocity of the bullet (A), Time of flight (B), Initial speed of the rifle (C), or Angle of elevation (D). Without context, it's unclear which specific piece of information is sought after for completing the problem. However, when dealing with projectile motion in physics, these are all critical factors that determine the bullet's trajectory and point of impact.
To answer a question like (a) from the provided references, where a gun is sighted to hit targets 100.0 m away, one would need to calculate the vertical displacement of the bullet due to gravity when it is aimed at a target 150.0 m away, given the muzzle velocity of 275 m/s. The time of flight would increase and, given gravity's constant acceleration, the bullet would hit lower than the intended target. For part (b), a larger muzzle velocity would result in a flatter trajectory and a longer range before the bullet drops significantly, reducing the effect of gravity. Air resistance would slow the bullet down, decreasing its range and causing it to drop sooner than it would in a vacuum.