Potential energy (in joule) of a particle of mass $1 \mathrm{~kg}$ moving in $x-y$ plane is $U=3 x+4 y$, here $x$ and $y$ are in meter. If at time $t=0$, particle is at rest at point $P(6 \mathrm{~m}$, $4 \mathrm{~m}$ ). Then
(A) acceleration of particle is $(3 \hat{i}+4 \hat{j}) \mathrm{m} / \mathrm{s}$.
(B) time when it crosses $y$-axis is $t=1 \mathrm{~s}$.
(C) speed of particle when it crosses $y$-axis is $10 \mathrm{~m} / \mathrm{s}$.
(D) it crosses $y$-axis at $y=-8 \mathrm{~m}$.