In 2013, Gregory invested $10,000 in a cattle-feeding partnership that used nonrecourse notes to purchase $100,000 of feed, which was used to feed the cattle and expensed. If Gregory's share of the expense was $20,000, what is the most that Gregory can deduct in 2013?
a. $10,000
b. $20,000
c. $30,000
d. $100,000