The tangents at $\mathrm{P}, \mathrm{Q}$ on $\mathrm{y}^{2}=4 \mathrm{ax}$ meet at $\mathrm{T}$, and $\mathrm{S}$ is the focus. If $\mathrm{SP}, \mathrm{ST}, \mathrm{SQ}$ are $\alpha, \beta, \gamma$ respectively, then the roots of $\alpha \mathrm{x}^{2}$ $+2 \beta x+\gamma=0$ are
(a) imaginary
(b) real and distinct integers
(c) real and equal
(d) real and irrational