Explanation:

• The 73rd Constitutional Amendment Act provides for the reservation of seats for scheduled castes and scheduled tribes in every panchayat (i.e., at all three levels) in proportion of their population to the total population in the panchayat area.
• Further, the state legislature shall provide for the reservation of offices of chairperson in the panchayat at the village or any other level for the SCs and STs.
• It must be noted here that the above provision relating to the reservation of seats in panchayats (both members and chairpersons) for the scheduled castes is not applicable to the state of Arunachal Pradesh.
• This is because the state is inhabited fully by indigenous tribal people and there are no scheduled castes.
• This provision was added later by the 83rd Constitutional Amendment Act of 2000.Hence, option (a) is the correct answer.