An object is propelled vertically upward from the top of a​ 256-foot building. The quadratic function​ s(t) = ​-16t squared ​+ 192t​ + 256 models the​ ball's height above the​ ground, s(t), in​ feet, t seconds after it was thrown. How many seconds does it take until the object finally hits the​ ground? Round to the nearest tenth of a second if necessary. A. 6 seconds