Explanation : Marshall, who propounded the theory that price is determined by both demand and supply, also gave a great importance to the time element in the determination of price. He introduced time period analysis into pricing process to bring out the varying influence of each of two forces over price of the product in different time periods. He said. "as a general rate". "the shorter the period which one considers the greater must be the share of our attention which is given to the influence of demand on value, and the longer the period more important will be the influence of cost of production on value." ....Read more