For each of the following situations, determine the proper year for recognition of the income or deduction if the taxpayer is (1) a cash basis taxpayer and (2) an accrual basis taxpayer:

a. Helen fixes Mark's plumbing in November 2019. Mark receives the bill in December 2019 but does not pay Helen until January 2020.

b. Siddaround, Inc. sells a mattress to Lorissa for $6,000. The terms of the sale call for Lorissa to pay $3,000 in the year of sale and $1,000 in each of the succeeding 3 years.

c. Maury's Computer Consultants, Inc. performs work for Janis in 2019. Maury's bills Janis in 2019, but no payment is received. In 2020, Janis files for bankruptcy, and Maury's determines that it will be able to collect nothing on her account.