Ali, a construction contractor builds an office building for construction partnership in exchange for a partnership interest in capital and profits. Ali's normal fee for his services is $400,000. Based on the appraised value of the office building, the fair market value of Ali's partnership interest is estimated at $500,000. What is Ali's outside basis in his partnership interest upon the completion of his construction services?

A. $400,000

B. $500,000

C. $0

D. None of the above