Direction: In a family of six, there are three men X, Y and Z and three women…

Key facts: from the problem statement

• There are two married couples and two unmarried persons.

• The Doctor is married to the Lawyer; the Lawyer is C's daughter-in-law, so the Doctor is a son of C (male child of C).

• X is married to the Chartered Accountant (CA).

• A's father is the Professor (so the Professor is a male parent of A).

• Y is not X's son, and Y is neither the Architect nor the Professor.

Deductions:

1. Because the Lawyer is C's daughter-in-law, the Doctor must be one of C's sons (a male child of C). The Doctor therefore is a male and cannot be X if X is married to the CA.

2. X is married to the CA; that pair is one married couple. The Doctor–Lawyer pair is the other married couple. The two remaining people are unmarried.

3. If X were not the Professor, then the Professor must be another male; but Y cannot be Professor, so the Professor is X or Z. A's father is the Professor, so A must be the child of that Professor.

4. A consistent assignment that satisfies all constraints is:

5. X = Professor (married to C, who is the Chartered Accountant).

6. Z = Doctor (son of C), married to B who is the Lawyer (so B is C's daughter-in-law).

7. Y is therefore the remaining unmarried male and cannot be Architect or Professor, so Y is the Engineer.

8. A is the remaining person and so must be the Architect.

Conclusion: A is the Architect.