for max height let dh/dx = 0 hence we get, -64x/4900 =-1 or x = 4900/64 =76.5625 (answer A)

H(76.5625) = -32 (76.5625) ^2/4900 +76.5625+190 =228.2813 Feet (answer B)

(c) the projectile was projected from an height of 190 ft (x = 0) . hence when it will touch the water ,height H will become -190 therefore -32x^2/4900 +x+190 = -190