Final answer:
An increase in the price of memory chips would likely decrease the supply of laptops, as it raises production costs and reduces the quantity producers are willing to supply.
Step-by-step explanation:
The event that would cause a decrease in the supply of laptop computers is B. The price of memory chips used in laptop computers rises. This is because an increase in the price of a key input, like memory chips, makes producing laptops more expensive, which typically reduces the quantity that producers are willing to supply at any given price. Option C would likely increase supply, as it indicates a decrease in production costs, while options A and D are related to changes in expectations about future prices, which might affect demand rather than supply.