Observing I, II and III, we find that similar letters have similar code symbols at the corresponding places in the code. So, this is direct-coding.

Thus, to find the code for DATE, we need the code for D which can be obtained from I only (i.e. $.) and the codes for A, T and E which can be obtained either from II or III (@, # and % respectively).

From I, the order is : E, B, C or C, B, E.

From II, the order is : E, B.

From III, the order is : A, D, E.

Combining the above three, we get the order as : A, D, E, B, C. Clearly, E is sitting in the middle.

From II, we conclude that in a class of 40, Deepak ranks 23rd from the bottom i.e. 18th from the top.

From I and II, we find that Suman is 3 ranks below 18th rank from the top i.e. she ranks 21st from the top.

From II and III, we find that Suman is 3 ranks above 23rd rank from the bottom

i.e. she ranks 20th from the bottom or 21st from the top.

From II, we know that N is K's son and K is B's grandfather. Thus, N is the son of B's grandfather i.e. N is either father or uncle of B.

From I, B is the daughter of M. So, M is either father or mother of B.

Clearly, the correct relationship between M and N cannot be deduced.

From II, we conclude that P is R's mother.

From I, we conclude that M is the brother or sister of P's husband, who is also R's father. Thus, R is either nephew or niece of M.