Two Statements S1 and S2 are given below with regard to four numbers P, Q, R and S followed by a Question:
S1: R is greater than P as well as Q.
S2: S is not the largest one.

Question: Among four numbers P, Q, R and S, which one is the largest?

Which one of the following is correct in respect of the above Statements and the Question?

Correct Answer: (C) S1 and S2 together are sufficient to answer the Question, but neither S1 alone nor S2 alone is sufficient to answer the Question.

From S1, the product of the two numbers is $xy = 21$, which alone has multiple pairs of factors. From S2, their sum is $x + y = 10$, which alone has infinite solutions. Combining both statements yields the quadratic equation $t^2 - 10t + 21 = 0$, giving $(t - 3)(t - 7) = 0$. Thus, the two numbers are uniquely determined as 3 and 7 using both statements together.