Ron, David, and Mary formed Widget, Inc. Ron and David each received 40% of the stock, and Mary received the remaining 20%. Ron contributed land with an FMV of $70,000 and an adjusted basis of $20,000. The corporation also assumed a $30,000 liability on the property. David contributed land with an FMV of $30,000 and an adjusted basis of $15,000. David also contributed $10,000 in cash. Mary received her stock for services rendered. She normally would bill $20,000 for these services. What is Ron's taxable gain as a result of this transaction?

a. $0

b. $10,000 

c. $20,000

d. $30,000