Three Statements S1, S2 and S3 are given below followed by a Question:

S1: C is younger than D, but older than A and B.
S2: D is the oldest.
S3: A is older than B.

Question: Who among A, B, C and D is the youngest?

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

The correct option is S1 and S3 together are sufficient to answer the Question.

To determine who among A, B, C, and D is the youngest, let us analyze the given statements step-by-step:

Analysis of Statement 1 (S1):
S1 states: "C is younger than D, but older than A and B."
From S1, we can write the order of age as follows:
D > C > A and B
This tells us that D is older than C, and C is older than both A and B. Thus, either A or B must be the youngest person, but S1 alone does not specify whether A is younger than B or vice versa.

Analysis of Statement 2 (S2):
S2 states: "D is the oldest."
This gives us information only about D (D > A, B, C). It does not provide any comparison between A, B, and C to help us find the youngest.

Analysis of Statement 3 (S3):
S3 states: "A is older than B."
In terms of inequality, this means A > B. S3 alone only compares A and B, so it is not sufficient on its own.

Combining Statements S1 and S3:
From S1, we established that C is older than both A and B (C > A and C > B), and D is older than C (D > C).
From S3, we know that A is older than B (A > B).
Combining these two statements gives the complete ordering from oldest to youngest:
D > C > A > B
Therefore, B is uniquely determined to be the youngest among A, B, C, and D.

Hence, statements S1 and S3 together are sufficient to answer the question.