Assuming that data mining approaches are to be used in the following cases, identify whether the task required is supervised or unsupervised learning:

a. Printing of custom discount coupons at the conclusion of a grocery store checkout based on what you just bought and what others have bought previously

b. Deciding whether to issue a loan to an applicant based on demographic and financial data, with reference to a database of similar data on prior customers.

c. Identifying a network data packet as dangerous (virus, hacker attack) based on comparison to other packets whose threat status is known.