- The Engineer is the son of the Accountant.
- The Accountant is not a blood relative of the Doctor.
- Therefore, the Accountant must be either the wife or the son (since the mother and Raj are blood relatives).
- The Lawyer is a blood relative of the Doctor.
- If the Doctor is Raj, then the Lawyer must be the mother or the son.
- But if Doctor = Raj, the Accountant would have to be the wife, and the Engineer = son of Accountant — this creates conflicts with the given constraints.
From the analysis, both Mr. Raj and Mr. Raj's son can never be the Doctor.
\[ \boxed{\text{Both A and C}} \]





For any natural number $k$, let $a_k = 3^k$. The smallest natural number $m$ for which \[ (a_1)^1 \times (a_2)^2 \times \dots \times (a_{20})^{20} \;<\; a_{21} \times a_{22} \times \dots \times a_{20+m} \] is: