[单选题]
A small object is fired horizontally at a l;bx likc9hh.b )tw;6s d94l: i8srlcmw -gpd0ke9d +(i xoi3ipeed of $300\,m\,s^{−1}$ from the top of a building. Air resistance is negligible. The object lands 900 m from the base of the building. What is the height of the building?