Correct Option: A. A decrease in the price of inputs used to produce the good Detailed Explanation: To understand why option A is the correct answer, we need to delve into the concept of supply in economics. Supply refers to the quantity of a good or service that producers are willing and able to sell at different prices over a certain period. The law of supply states that, all else being equal, an increase in the price of a good will lead to an increase in the quantity supplied, and vice versa. Step-by-Step Explanation of Option A:

1. Understanding Inputs: Inputs are the resources used in the production of goods. These can include raw materials, labor, machinery, and other factors of production. The cost of these inputs directly affects the overall cost of production.
2. Impact of Input Prices on Supply: When the price of inputs decreases, it becomes cheaper for producers to manufacture their goods. This reduction in production costs allows suppliers to increase their profit margins or maintain the same profit margins while selling at lower prices.
3. Shifting the Supply Curve: A decrease in input prices shifts the supply curve to the right. This means that at every price level, producers are willing to supply more of the good than before. For example, if the cost of steel (an input for car manufacturing) decreases, car manufacturers can produce more cars at a lower cost, thus increasing the overall supply of cars in the market.
4. Market Dynamics: In a competitive market, as supply increases, the market equilibrium price may decrease, leading to a higher quantity of goods sold. This is beneficial for consumers as it can lead to lower prices.

Why the Other Options Are Incorrect: B. An increase in consumer income: - This option relates to demand rather than supply. When consumer income increases, people generally have more money to spend, which can lead to an increase in demand for goods. However, this does not directly affect the supply side. An increase in demand can lead to higher prices, which might incentivize suppliers to produce more, but it does not directly cause an increase in supply. C. A rise in the price of the good itself: - While a rise in the price of the good can lead to an increase in the quantity supplied (as per the law of supply), it does not inherently increase the overall supply. Instead, it may lead to a movement along the supply curve rather than a shift of the supply curve itself. The supply curve shifts when factors other than the price of the good change, such as input costs. D. A decrease in the number of suppliers in the market: - A decrease in the number of suppliers would likely lead to a decrease in supply, not an increase. Fewer suppliers mean less competition and potentially less overall production of the good, which would shift the supply curve to the left. Summary of Key Points:

• Supply and Inputs: A decrease in input prices lowers production costs, allowing suppliers to increase the quantity supplied.
• Supply Curve Shift: Lower input costs shift the supply curve to the right, indicating an increase in supply at all price levels.
• Demand vs. Supply: Options B and C relate to demand dynamics and do not directly increase supply.
• Market Structure: A decrease in the number of suppliers (Option D) reduces overall market supply.

Revision Summary:

• A decrease in input prices leads to an increase in supply by reducing production costs.
• Supply curves shift right with lower input costs, allowing more goods to be produced.
• Demand factors (like consumer income) do not directly affect supply.
• Fewer suppliers in the market decrease overall supply, contrary to increasing it.