Goodwill question help please

Hi all, wondering why the answer to the below CFA Q is not both A and B? My understanding is goodwill will be measured as the premium of the net assets of the acquired company vs the purchase price. Book says answer is A.

Q) the initial measurement of goodwill is most likely affected by:
a) an acquisitions purchase price
B) the acquired company’s book value
C) the fair value of the acquirers assets and liabilities


Goodwill is measured as the acquisition purchase price - fair value of acquiree assets/liabilities.