The term scarcity in economics refers to the fact that:
a. economic wants are limited and resources are abused
b. even in the riches country some people go hungry
c. no country can produce enough products to satisfy everybody's economic wants
d. it is impossible to produce too much of any particular good or service in a market economy
True because of supply and demand. If the demand is higher than the supply, or people cannot afford the supply, the demand must decrease in value so that people can facilitate the supply and keep it going.
Answer and explanation:
If no bands were visible on the gel for some samples I'd interpret this result as in a very possible pippeting error that did not allow the sample to load correctly. Pippeting error can be caused by many factors, for example, if our chosen pipet is broken or dirty this can cause amount of liquid reduction after the transfer process.