(a) Explain why each of the following factors may influence the own price elasticity of demand for a commodity.
(i) Consumer preferences, that is, whether consumers regard the commodity as a 'luxury'' or a 'necessity''.
(ii) The narrowness of definition of the commodity.
(iii) The length of the period under consideration
(iv) The availability of substitutes for the commodity
Write your response in 1000-1200 words count.