b. Shortage
Explanation:
If the demand of a new product is greater than expected, it means that the manufacturers did not produce or were not able to have enough product in their stock to satisfy the demand, so they're experiencing a shortage.
This is a common scenario when a company launches a new product, because there's no previous known history that can be used for a demand forecast.
It's important to not confuse shortage with scarcity, because they differ in the sense that something that is scarce is rare or difficult to find or produce, but a shortage simply means that the supply was not enough to satisfy the demand. They could have produced a larger quantity of this new product, but their expectation was amiss, so they cannot satisfy the demand.