Concept:Joint supply occurs when two commodities are produced together from the same source or process.
Explanation:When the supply of commodity
X rises automatically, the supply of commodity
Y also rises because both are jointly produced.
This means
X and
Y are by-products of the same production process.
For example, producing more crude oil also increases the supply of petrol and kerosene.
Therefore, a rise in one good directly causes a rise in the other good.
This relationship is not elastic supply, exceptional supply, or competitive supply.
Answer:B. joint supply