Correct Answer - `L ; LT^(-1) ;s LT^(-2) ; LT^(-3)`
As LHS of given relation is distance, every term
on RHS must represent distance.
:. a = x = L
`bt = x, b =x//t = L//t = LT^(-1)`
`ct^2 = x,c = x//t^2 = L//T^2 = LT^(-2)`
`dt^3 = x,d =x//t^3 = L//T^3 = LT^(-3)`