A bullet is fired upward from ground level. Its height above the ground​ (in feet) at time t seconds is given by the following equation.   ​H(t)=-16t^2 + 992t   ​(a) Find the vertex. ​(b) Find the time at which the bullet reaches its maximum height. ​(c) Find the maximum height. ​(d) Find the time at which the bullet hits the ground​ (when the height is equal to​ zero). ​(a) What equation can be used to calculate the​ t-coordinate of the​ vertex?     A. tequals=negative StartFraction 992 Over 2 left parenthesis negative 16 right parenthesis EndFraction−9922(−16)   B. tequals=StartFraction 2 left parenthesis negative 16 right parenthesis Over 992 EndFraction2(−16)992   C. tequals=StartFraction 992 Over 2 left parenthesis negative 16 right parenthesis EndFraction9922(−16)   D. tequals=negative StartFraction 2 left parenthesis negative 16 right parenthesis Over 992 EndFraction−2(−16)992 The vertex is at nothing. ​(Type an ordered pair. Do not use commas in the individual​ coordinates.) ​(b) The bullet reaches at maximum at nothing seconds. ​(Type a whole​ number.) ​(c) The maximum height of the bullet is nothing feet. ​(Type a whole​ number.) ​(d) The bullet hits the ground at nothing seconds. ​(Type an integer or a​ decimal.)