[单选题]
A fighter plane moving 200 kf1cq vmt:k+4 m/s ho i0rm9a1jo0ktrizontally fires a projectile with speed 50.0 m/s in a forward direction 0m1troijk 9a 0$30.0^{\circ}$ below the horizontal. What is the speed of the projectile with respect to a stationary observer on the ground?
