$B$ of $30$

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

the free$-$rider problem.

adverse selection.

asymmetric information.

moral hazard.

a public good.