Please submit your concern

Explanation:

Consider the following arrangement 

___   ___   ___
___   ___   ___

Here, the upper row corresponds to the houses facing south and the lower row corresponds to the houses facing north. 

It is given that Prof. Rathor gets a south facing flat next to Prof. Usman. Therefore, Prof. Usman also gets a south facing flat. 

It is also given that Prof. Qureshi and Prof. Tripathy have a north facing flat. 

Since it is known that Prof. Usman and Prof. Sawant are diagonally opposite each other, Prof. Sawant has to be in a north facing flat and so, Prof. Purohit has to be in a south facing flat. 

Thus, Prof. Usman, Prof. Rathor and Prof. Purohit get south facing flats. 

Hence, option (c).