Answer:
d. the supply of leather (a complement in production)
Step-by-step explanation:
According to the law of demand, the demand of the commodity rises when the price is less and the demand for the commodity falls when the price is high. One of the factors affecting the law of demand is the availability of related goods. The price of the goods which is a substitute for the commodity also increases with the increase in the price. At the same time, if the price of the commodity decreases, the price and the demand for the substitute will also decrease.