In economic language, a shortage is best defined as
a.

a situation in which the demand for a good or service is greater than the amount supplied in a market
b.

an ongoing condition of limited resources to meet unlimited needs and wants
c.

too many businesses selling a product and not enough people who want to buy it
d.

a situation in which people need to be very careful with what they have because they might not be able to afford more

I believe that the best answer for this question is B, "an ongoing condition of limited resources to meet unlimited needs and wants." You can reach this conclusion by considering the meaning of "shortage," which is defined as a situation where something that is needed cannot be sufficiently gained. You can also use the process of elimination. A lays out the opposite of a shortage. C is also pretty much the opposite definition of a surplus. D is closer, but in this situation, people are still able to afford things they need but are not necessarily in a shortage. Hope this helps.