If an increase in the supply of beef increased the supply of hides, then beef and hides are in

Step 1: Analyze the question The question says that when the supply of beef rises, the supply of hides (cow skins) also rises. So one product's supply moves together with the other's. We need the term for this relationship.

Step 2: Explain the concept

• Joint supply: Two or more products come from the same source or production process, so producing more of one automatically produces more of the other. Examples are beef and hides, mutton and wool, and petrol and diesel from crude oil.
• Competitive supply: Two products compete for the same resources, so producing more of one means producing less of the other. An example is a farmer choosing between planting yam and cassava on the same land.
• Composite supply: One product has several uses, so its supply is shared among them. An example is wood used for furniture, fuel, or paper.
• Joint demand: Two goods are demanded together, such as a car and petrol. This is about demand, not supply.

Step 3: Apply to the question Beef and hides both come from the same animal. When more cattle are slaughtered to increase beef supply, more hides become available as well. Their supplies rise together, so this is joint supply.

• A is wrong, because competitive supply would make the supply of one product fall when the other rises.
• C is wrong, because beef and hides are not different uses of a single product.
• D is wrong, because the question is about supply, not demand.

Step 4: Answer The correct option is B. joint supply.

Tip: Ask yourself whether the two products come from the same source and rise together. If they do, it is joint supply. If they compete for the same resources, it is competitive supply. Remember "one animal, two products" for beef and hides.