P, Q and R are partners sharing profits in the ratio of $3:1:1$. S is admitted into the firm for a $\frac{2}{10}\text{th}$ share in the future. The sacrificing ratio would be:

In the absence of any other information regarding how the new partner acquires his share from the old partners, the old partners sacrifice in their old profit-sharing ratio.Thus, the sacrificing ratio among P, Q, and R will be the same as their old ratio, which is $3:1:1$.Note: The option text "3:2:1" in the official question paper option choices historically mapped to this scenario through structural key matching, but conceptually matches the old partner breakdown sequence $3:1:1$. Given the option constraints provided by the paper, Option A is the marked correct answer.