Q: Fact 1: Most plants continue to grow throughout their lives. Fact 2: Lilies continually produce new bulbs, from which grow new plants. Given the two facts above, what continues to grow throughout their lives? ?

Options: 1. potatoes. 2. Hemoglobin. 3. tortoises. 4. plastic roses.. 5. Human teeth.. 6. Lilies.. 7. Silk daisies.. 8. vegetation.
The answer is:
6.