Barbara Beck, CPA has gathered the following information during the audit of Smith Company, Inc. for the calendar year ended December 31, 2017: When reviewing the accounts receivable subsidiary ledger, Barbara found that accounts had been sold to a factoring agent, but not removed from the books. What specific assertion does this piece of information apply to?

a. Completeness

b. Rights and obligations

c. Occurrence

d. Valuation and allocation

e. Cutoff