The co-ordinates of a moving particale at any time t are given by x= \( \alpha \) t³and y= \( \beta \) t³.The speed to the particle at time t is given by -----

A 3t \( 3 t \sqrt{\left ( \alpha 2 + \beta 2 \right.} \)

B \( 3 t^ 2 \sqrt{\left ( \alpha 2 + \beta 2 \right.} \)

C \( t \sqrt{\alpha} + \sqrt{\beta} \)