If all eight persons are asked to sit in an alphabetical order from right to left, the position of how many will remain unchanged as compared to their original seating position ?

E is to the immediate right of A and G is an immediate neighbour of A, => G is to the immediate left of A.

D is sitting fifth to the right of E and F is sitting fifth to the right of A, => G is sitting at extreme left end while D is sitting at extreme right end.

B is third to the right of G, => B sits to the immediate right of E. 

H is third to the left of D, => H sits to the immediate right of B and the vacant place, i.e. between H and F is filled by C. 

If all eight persons are asked to sit in an alphabetical order from right to left, the position of only C will remain unchanged as compared to their original seating position.

=> Ans - (C)