Roger is a 30% partner in the ROC Partnership. At the beginning of the tax year. Roger's basis in partnerhips interest was $60,000, including his share of partnership liabilities. During the current year, ROC reported a net ordinary income of $40,000. In addition, ROC distributed $5,000 to each of the partners ($15,000 total). At the end of the year, Roger's share of partnership liabilities increased by $20,000. Roger's basis in the partnership interest at the end of the year is:
a. $60,000
b. $75,000
c. $87,000
d. $120,000
e. none of the above