Tangents and normal drawn to the parabola `y^2=4a x` at point `P(a t^2,2a t),t!=0,` meet the x-axis at point `Ta n dN ,` respectively. If `S` is the focus of theparabola, then `S P=S T!=S N` (b) `S P!=S T=S N` `S P=S T=S N` (d) `S P!=S T!=S N`