The charge flowing in a conductor changes with time as \( Q(t)=\alpha t-\beta t^{2}+\gamma t^{3} \). Where \( \alpha, \beta \) and \( \gamma \) are constants. Minimum value of current is :
[Jan. 30, 2023 (I)]
(a) \( \alpha=\frac{3 \beta^{2}}{\gamma} \)
(b) \( \alpha-\frac{\gamma^{2}}{3 \beta} \)
(c) \( \beta-\frac{\alpha^{2}}{3 \gamma} \)
(d) \( \alpha-\frac{\beta^{2}}{3 \gamma} \)