(A) $a _{ x }=1 \,ms ^{-2}$ implies that when the particle is at the origin, $a _{ y }=1 \,ms ^{-2}$
(B) $a _{ x }=0$ implies $a _{ y }=1\, ms ^{-2}$ at all times
(C) at $t =0$, the particle's velocity points in the $x$-direction
(D) $a _{ x }=0$ implies that at $t =1 s$, the angle between the particle's velocity and the $x$ axis is $45^{\circ}$