Step 1: Identify who could possibly be the MD.
The highest of the four salaries, Rs 40,000, Rs 50,000, Rs 60,000 and Rs 70,000, is Rs 70,000, and this belongs to whoever is the MD, since the MD earned the most.
Biswajeet is the lawyer and Dhruv is the engineer, so the MD must be either Arvind or Chinmay.
Step 2: Work out the other three salaries first.
Biswajeet and Dhruv both avoided Rs 50,000, so Rs 50,000 must belong to the Doctor, whichever of Arvind or Chinmay is not the MD.
Since the Doctor earned more than Dhruv, Dhruv's salary is below Rs 50,000, fixing Dhruv at Rs 40,000 and leaving Biswajeet with Rs 60,000.
Step 3: Decide between Arvind and Chinmay for the MD role.
The clue Arvind earned more than Biswajeet means Arvind's salary must exceed Rs 60,000.
If Arvind were the Doctor, he would earn only Rs 50,000, which is less than Biswajeet's Rs 60,000, so that cannot be right. Arvind must instead be the MD, earning Rs 70,000, which is indeed more than Rs 60,000. Chinmay then takes the Doctor's role and salary of Rs 50,000.
Step 4: Compare all four final salaries.
Arvind, Rs 70,000. Biswajeet, Rs 60,000. Chinmay, Rs 50,000. Dhruv, Rs 40,000. The largest of these four figures is Rs 70,000, held by Arvind.
Final Answer:
Arvind received the highest starting salary.
\[ \boxed{\text{Arvind}} \]