[单选题]
A small object is firedq,z w5n.l7 eljkvj:uw* ywd 83 horizo * gz/rp9e4fyvzy()qb ntally at a speed 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?