The basis of a partner's interest in a partnership is increased by:

a. Decreases in partnership liabilities

b. Receipt by the partnership of an item of income that is excluded from the definition of gross income

c. Gain recognized by another partner when the other partner sells an interest in the partnership at a gain

d. Payment by the partnership of nondeductible expense

e. Issuance of a promissory note to the partnership to pay for an additional interest in the partnership.