Teri takes her new puppy to the veterinarian. After he examines the puppy, the vet tells Teri that her puppy needs a series of shots. Teri agrees to the shots since the veterinarian knows way more about animal health than she does. This is an example of

a. a public good.
b. moral hazard
c. the free-rider problem.
d. adverse selection.
e. asymmetric information.