Some regions of our country still remain ...... to the average man.

Solution (By Examveda Team)

Some regions of our country still remain inaccessible to the average man.
In this context, "inaccessible" means not easily reached or entered, implying that certain regions are difficult for the average person to access. Therefore, "inaccessible" is the most appropriate choice to complete the sentence, accurately describing the difficulty in reaching these regions.