It is known as the opening statement
Answer:
1. Circulatory System
2. White Blood Cells
3. Capillaries
4. Vein
5. Carbon Dioxide (CO²)
6. Circulatory System
7. Immune System , Fights
8. Red Blood Cells
9. Gas Exchange
10. Transport
11. Lungs
12. Artery, Heart and Lungs
13. Heart
14. Important Plant
15. Alveoli
I think this is ether b. Trait or C. Allele, pretty sure it’s allele though. Good luck!