Ronald Is a Cash Method Taxpayer Who Made the Following

Ronald is a cash method taxpayer who made the following expenditures this year. Which expenditure is completely deductible in this period as a business expense?

A) $55 to collect an account receivable from a customer who has failed to pay for services rendered.
B) $4,000 for rent on his office that covers the next 24 months.
C) $2,500 for professional hockey tickets distributed to a customer to generate "goodwill" for his business.
D) $3,000 for a new watch for the mayor to keep "good relations" with city hall.
E) None of the choices are completely deductible.