Which of the following sources of tax law may NOT be relied upon by a taxpayer?

1. Proposed Regulations
2. Revenue Rulings.
3. Private Letter Rulings.
4. Temporary Regulations. answer choices:
   1. 1 and 3.
   2. 2 and 4.
   3. 2 and 3.

d. 1, 2, and 3.