Near year-end, P, a cash basis, calendar year taxpayer, paid for various deductible expenses as described below.

1. The payment was dropped in the mail before year-end.
2. P gave a note evidencing her promise to pay the amount in three months.
3. The amount was charged on her Master Card on December 28. The charge appeared on her bill for the period December 1 through December 31, which she received in January and which she paid on January 20. The bank actually paid the expense in January.
4. The amount was paid using the pay-by-phone service provided by her bank. P called in the charge on December 20. The bank sent her a statement indicating that it had paid the charge on January 3.

P may deduct the expense in which cases?