Compound ratio is the ratio of product of first terms in every ratio to that of product of second term in every ratio. Thus, inverse ratios of the ratios of x : yz , y : zx , z : xy  = $$frac{yz}{x}$$ , $$frac{zx}{y}$$ , $$frac{xy}{z}$$ Product of ratios = $$frac{x^2y^2z^2}{xyz}$$ = $$frac{xyz}{1}$$ Thus, compound ratio = xyz : 1 => Ans - (B)