Vicki is shopping for books. She prefers Great Expectations to The Chosen and prefers The Chosen to Jurassic Park. She buys Great Expectations and Jurassic Park for a total of $30. Which of the following MUST be true?
a. Her PIBP for Jurassic Park is greater than $15.
b. Her PIBP for Great Expectations is greater than $15.
c. Her PIBP for Jurassic Park is less than $15 .
d. None of the above.