A proton , a deutron and alpha particle are accelerated through potentials of $\;V , 2V ,4V\;$respectively . Their velocity will bear a ratio .

Question

$(a)\;1 :1 :1\qquad(b)\;1 :\sqrt{2} : 1\qquad(c)\;\sqrt{2} : 1: 1\qquad(d)\;1 : 1 : \sqrt {2}$