Correct Answer - Option 4 : Professor, Engineer, Doctor, MLA, IAS officer
Five flats and five professionals.
i) The professor has to go up to meet his IAS officer friend.
Top : IAS > Professor : Bottom
ii) The doctor is equally friendly to all, and has to go up as frequently as go down.
Top : __ > __ > Doctor > __ > __ : Bottom; Top : IAS > Professor : Bottom
iii) The engineer has to go up to meet his MLA friend above whose flat lives the professor's friend.
Top : __ > __ > Doctor > __ > __ : Bottom; Top : IAS > Professor : Bottom; Top: IAS > MLA >Engineer : Bottom;
Case 1: Top : IAS > MLA > Doctor > Engineer/ Professor > Professor / Engineer : Bottom
Here, we know that 'IAS Officer' lives on the top floor.
Hence, 'Professor, Engineer, Doctor, MLA, IAS officer' from ground to top floor is the correct answer.