An increase in the supply of a commodity X automatically results in an increase in the supply of another commodity Y. This is a cause of

The situation described in the question is known as joint supply. Joint supply is a phenomenon that occurs when the production of one commodity leads to the production of another commodity. In this case, an increase in the supply of commodity X leads to an increase in the supply of commodity Y. Joint supply occurs because the two commodities are produced using the same inputs, and the production of one commodity generates a byproduct that can be used to produce the other commodity. An example of joint supply is the production of beef and leather. When a cow is slaughtered for its meat, the skin can be used to produce leather, so an increase in the supply of beef leads to an increase in the supply of leather. Joint supply is different from competitive supply, which occurs when two commodities compete for the same inputs. In the case of competitive supply, an increase in the supply of one commodity leads to a decrease in the supply of the other commodity.