The trajectory of a projectile in a vertical plane is y=αx−βx2, where α and β are constants and x & y are respectively the horizontal and vertical distances of the projectile from the point of projection. The angle of projection θ and the maximum height attained H are respectively given by
(a) tan−1α,β4α2
(b) tan−1β,2βα2
(c) tan−1(αβ),βα2
(d) tan−1α,4βα2