Explanation:

- Option 1: Flowers

- Flowers are not typically flame retardants. They are organic and can burn easily when exposed to fire.

- Option 2: Skin

- Human or animal skin is not a flame retardant. It is not designed to withstand or resist fires.

- Option 3: DNA

- Correct Answer: DNA has shown some flame-retardant properties due to its phosphorus content and ability to form a char layer when exposed to heat. This can help prevent the spread of fire.

- Option 4: RNA

- Like DNA, RNA is not commonly identified as a flame retardant and does not have the necessary structure to serve as one.