Which of the following statements is in accordance with De-Morgan’s second theorem

Which of the following statements is in accordance with De-Morgan’s second theorem:

1. A NAND gate is equivalent to bubbled AND gate
2. The AND gate is equivalent to bubbled NAND gate
3. A NAND gate is always complementary to an AND gate
4. A NAND gate is equivalent to bubbled OR Gate

Correct answer: 4. A NAND gate is equivalent to bubbled OR Gate