With reference to Indian history, which of the following is/are the essential element/elements of the feudal system?
i) A very strong centralized political authority and a very weak provincial or local political authority
ii) Emergence of administrative structure based on control and possession of land
iii) Creation of lord-vassal relationship between the feudal lord and his overlord

Select the correct answer using the code given below.
a) i and ii only
b) ii and iii only
c) iii only
d) i, ii and iii