Step 1: Arrange the known facts
- Four salaries: 40k, 50k, 60k, 70k.
- MD = highest salary = 70k.
- Arvind>Biswajit.
- Doctor>Dhruv (engineer).
- Lawyer ≠ 50k, Dhruv ≠ 50k.
Step 2: Logical deductions
1. Since the doctor earned more than Dhruv, Dhruv cannot have 70k (that's already MD).
2. Lawyer's salary cannot be 50k.
3. If Dhruv ≠ 50k, and is not MD, then Dhruv must have 40k or 60k.
Step 3: Matching conditions with Arvind>Biswajit
- If Arvind is the doctor (possible), then Dhruv (engineer) is lower paid.
- Lawyer must have a salary consistent with all constraints — 60k fits perfectly: not 50k, more than Dhruv if Dhruv has 40k, and less than MD with 70k.
Step 4: Conclusion
The lawyer's starting salary was ₹ 60,000.
\[
\boxed{\text{Answer: (C) 60,000}}
\]